Hailed by Michael Salfino of the Wall Street Journal and Yahoo! Sports for its “insightful and often contrarian viewpoint to prospect rankings,” the Prospect Digest Handbook is a perennial favorite among baseball enthusiasts, minor league fans, and fantasy general managers. Now back for its fifth season, the Prospect Digest Handbook is the definitive guide to the minor leagues.

1. Forrest Whitley, RHP

Background: Fun Pact Part I: Among all minor league hurlers with at least 90 innings last season, Whitley’s strikeout percentage, 37.6%, was the second best mark, trailing only the Pirates’ punch out artist Tyler Glasnow. Fun Fact Part II: Since 2006, no teenager has posted a better strikeout percentage than Whitley’s dominant showing last season (min. 90 IP). Fun Fact Part III: Whitley’s strikeout-to-walk percentage, 28.7%, last season was the second best mark, trailing – once again – Pittsburgh’s Tyler Glasnow. Fun Fact Part IV: Whitley’s strikeout-to-walk percentage is the best mark for any teenager since 2006 (min. 90 IP). Fun Fact Part V: Whitley’s 28.7% strikeout-to-walk percentage was the fourth best mark since 2006, trailing only Glasnow, Danny Salazar, and Rich Hill.

Turns out the behemoth right-hander out of Alamo Heights High School had a pretty historical year in 2017.

Taken with the 17th overall pick just two years ago, the 6-foot-7, 240-pound budding ace made three brief – and incredibly dominant – stops on the minor league ladder last season, going from the Low Class A to the High Class A before settling in for a four-game cameo with the Corpus Christi in the Texas League. When the dust finally settled, Whitley tossed 92.1 innings, recording a mind-boggling 143 strikeouts and just 34 walks. He finished the year with an aggregate 2.83 ERA and a 2.31FIP.

Projection: So let me ask this: Is Forrest Whitley the greatest teenage pitching prospect over the last decade? Last couple of decades? I don’t pretend to know that answer, but you could make an awfully strong case for that – at the very least on a year-to-year basis. Oh, one more thing: Despite throwing fewer than 100 innings last season, Whitley’s raw strikeout total, 143, tied for the 40th best mark among all minor league arms.

Consider the following:

Between 2006 and 2014, only one 19-year-old pitcher posted at least a 30% strikeout percentage with a double-digit walk percentage in the South Atlantic League (min. 40 IP): Tyler Glasnow.

Between 2006 and 2014, only one 19-year-old pitcher posted at least a 30% strikeout percentage in the Carolina League (min. 30 IP): John Lamb, who was widely recognized at the time as one of the top pitching prospects in the minors, though injuries would later derail his career.

Simply put, Whitley’s everything you’d want in a pitching prospect: huge (6-foot-7 and 240 pounds) and projectable, can control the strike zone, misses a metric ton of bats, and has exceeded against significantly older competition. He’s one of the very few pitching prospects that have a legitimate chance at reaching true ace-dom in the big leagues.

Ceiling: 6.5-win player

Risk: Moderate

MLB ETA: 2018/2019

2. Kyle Tucker, OF

Background: The younger brother of former Astros outfielder Preston Tucker, who was recently designated for assignment and later traded to the Braves for cash. Houston grabbed Preston’s lil sibling in the opening round of the 2015 draft out of H.B. Plant High School in Tampa, Florida. Tucker, the fifth overall pick, has the look of a franchise cornerstone for the next decade-plus. The toolsy outfielder was a bit overwhelmed during his debut in 2015, hitting an aggregate .246/.294/.353 between both of the club’s stateside rookie leagues. But he rebounded nicely in the Midwest League the following year, slugging .276/.348/.402 with 19 doubles, five triples, and six homeruns before earning a 16-game cameo with Lancaster. Houston bounced the then-20-year-old slugger back down to the Florida State League last season. But after battering the competition to the tune of .288/.379/.554, the club deemed him ready to take on the minors’ toughest challenge: Class AA. And Tucker was ready. Appearing in 72 games with the Corpus Christi Hooks, the 6-foot-4, 190-pound lefty-swinging prospect batted an impressive .265/.325/.512. And despite earning just a smidgeon over 300 plate appearances in the Texas League, Tucker’s 16 homeruns tied for the eight highest total in the league.

Overall, Tucker capped off his third professional season with an aggregate .274/.346/.528 triple-slash line while setting career highs in doubles (33) and homeruns (25) to go along with five triples and an underrated 21 stolen bases. His overall production, according to Weighted Runs Created Plus, topped the league average mark by 41%.

Projection: Here’s what I wrote about Tucker when I ranked him as the club’s second best prospect in last year’s Handbook:

“He can certainly fill a stat sheet with tons of extra-base pop and above-average speed. The lefty-swinging outfielder also handled lefties and righties without a hitch as well. But perhaps the best news is his plate discipline against much older pitching: he posted an 81-to-50 strikeout-to-walk ratio. A year-plus into his development and there’s very little red flags, if any, with tons of room to grow.”

Tucker took had quite the growth spurt in 2017. He set several career highs including the aforementioned doubles (33) and homeruns (25) as well as overall production (141 wRC+). So let’s take a look at his production in both the Carolina and Texas Leagues. This time, though, through a historical lens. Consider the following:

Between 2006 and 2015, here’s the list of 20-year-old hitters to post at least a 145 wRC+ mark in the Carolina League (min. 200 PA): Eric Hosmer, Mookie Betts, Joey Gallo, and Clint Frazier. And here are their respect career wRC+ totals in the big leagues: 111 (Hosmer), 122 (Betts), Gallo (111), and 82 (Frazier, who just made his much anticipate debut last season).

That’s a pretty solid collection of big league hitters. So let’s take a look at his production in the Texas League. Consider the following:

There was only one 20-year-old hitter – Billy Butler – who posted a wRC+ between 125 and 135 in the Texas League between 2006 and 2015 (min. 300 PA). Butler, by the way, owns a career 114 wRC+ mark in the big leagues.

Granted it’s not the be all, end all in terms of studies, but this should provide at least a strong baseline for Tucker’s impending big league future. Defensively speaking, he’s a bit miscast in center field, according to Clay Davenport’s defensive metrics, but he’s generally graded out as a slightly better-than-average left or right fielder. Ultimately, Tucker, like Betts, has the potential to reach the 25/25 plateau.

Ceiling: 5.0- to 5.5-win player

Risk: Low to Moderate

MLB ETA: 2018

Background: In a word: dominant. The hard-throwing right-hander, who hails from Ashburn, Virginia, has simply been one of the best pitchers at whichever level he’s performed. After helping his prep team, the Stone Bridge Bulldogs, to a district title, the generously listed 6-foot, 196-pound right-hander committed to the University of North Carolina – as a freshman. In high school. Following another Bob Gibson-esque sophomore season, Bukauskas reclassified during the summer in order to attend college one year earlier. Then during his junior campaign he went a perfect 7-0 while fanning nearly 90 hitters without allowing an earned run. And that string of strong performances continued for the Tar Heels in 2015, his freshman year, as well.

On a pitching staff that had several notable eventual MLB draft picks (fellow Astros prospect Trent Thornton, Zac Gallen, Trevor Kelley, and Benton Moss), Bukauskas stood out among his peers – easily. In 14 starts that year, he threw 72.2 innings with 67 strikeouts, 30 walks, and a 4.09 ERA – all at the tender age of 18. The eventual first round pick followed that up with an even more impressive showing the next season: 78.1 IP, 111 K, just 29 walks, and a 3.10 ERA. Bukauskas also starred for Team USA that summer as well, throwing 21.2 innings without allowing an earned run while fanning 21 and walking just three. He also made two brief starts with the Chatham Anglers that summer too, posting an ace-like 17-to-2 strikeout-to-walk ratio in just 9.2 innings of work. Last season Bukauskas continued to confound Division I hitters: in a career high 15 starts, he tossed 92.2 innings, racking up 116 punch outs against just 37 free passes en route to totaling a career best 2.53 ERA. For his collegiate career, he averaged 10.84 strikeouts and 3.54 walks per nine innings. Houston grabbed Bukauskas, my favorite arm in the entire draft class, with the 15th overall selection last June and signed him to a smidgeon above the recommended slot bonus. The diminutive righty made three brief appearances between the Gulf Coast and New York-Penn Leagues during his debut, throwing 10.0 innings with nine strikeouts and five walks.

Projection: Per the usual, here’s what I wrote about Bukauskas heading into last year’s draft:

“Pure. Filthy. Dominance. Consider the following:

Since 2011, here is a list of Division I pitchers to average at least 12 strikeouts and fewer than three walks every nine innings with an ERA below 2.00 (minimum 70 innings): Trevor Bauer, Danny Holtzen, Jack Leathersich, and Luke Gillingham. If the season ended today, Bukauskas would be the fifth member of the group.

Easily my favorite pitcher in the entire draft class. The lone knock on Bukauskas is his frame size. With that being said, though, the North Carolina coaching staff has done a fine job limiting his workload throughout his amateur career. Big, big time strikeout ability with better-than-average control. Bukauskas’s production is far more impressive than former Tar Heel – and 2010 seventh overall pick – Matt Harvey. If his likely sub-6-foot frame can prove to handle the rigors of taking the ball every fifth day in professional baseball, he has the potential to blossom into a bonafide frontend starter.”

Ceiling: 4.0-win player

Risk: Moderate

MLB ETA: 2019/2020

Background: Originally signed by the Los Angeles Dodgers for $2 million (plus another $2 million because the club exceeded the tax threshold), Houston acquired the hulking first baseman a few weeks later in exchange for veteran flame-throwing reliever Josh Fields. Alvarez, a native of Las Tunas, Cuba, popped up in the Cuban National Series for two seasons before defecting stateside. The 6-foot-5, 225-pound first baseman/corner outfield looked –as expected – completely overwhelmed in the foreign professional league as a 16-year-old, hitting a lowly .196/.275/.258. But he hardly resembled the light-hitting first baseman the following year: in 40 games with Lenadores de Las Tunas, Alvarez slugged an impressive .351/.402/.387, though he belted out just two extra-base hits (a double and a homerun). Houston sent their latest Cuban-import to the Dominican Summer League for a 16-game cameo two years. And the then-19-year-old responded exceedingly well: he slugged .341/.474/.500. The front office bounced Alvarez into the Midwest League at the start of 2017. And, once again, he completely dominated: he batted .360/.468/.658 with six doubles and nine homeruns in just 32 games. He spent the remaining schedule with the Buies Creek Astros in the Carolina League, hitting .277/.329/.393. Alvarez finished the year with an aggregate .304/.379/.481 triple-slash line with 17 doubles, three triples, and 12 homers. The sneaky quick gargantuan also swiped eight bags in nine tries. His overall production, according to Weighted Runs Created Plus, topped the league average mark by 39%

Projection: There are really two different stories to tell:

Alvarez’s dominance in the Midwest League: he did more damage in 32 games than many other top prospects do in an entire season. It was a historic-type level of production. Only three hitters have eclipsed the 200 wRC+ mark in the Midwest League since 2006 (min. 100 PA): Alvarez, Toronto’s Bo Bichette, and Nic Crosta, whose run in professional baseball extended across just two seasons. Alvarez’s mediocrity in the California League. Sure, he was only 20-years-old, but he was essentially a league-average High Class A.

So which one is he? He’s clearly not the slugger he showed in the Midwest League, but he’s also not the boring, vanilla bat that popped up in the California League. And he finished significantly better, hitting .319/.347/.434 over his final 28 contests. The frame size and power potential are incredibly, incredibly promising. There’s a little Nolan Arenado here – maybe.

Ceiling: 3.0- to 3.5-win player

Risk: Moderate

MLB ETA: 2019/2020

5. Rogelio Armenteros, RHP

Background: Houston signed the Cuban import, who was just 20-years-old at the time, for a bargain basement price of just $40,000 following the 2014 season. Three full seasons later Armenteros is knocking – loudly – on the big league club’s door. Keeping with the general theme of his stateside professional career, the 6-foot-1, 215-pound right-hander made multiple stops along the minor league develop ladder last season. Armenteros opened the year up in dominant fashion in the Texas League: he posted an impressive 18-to-3 strikeout-to-walk ratio over his first two starts, spanning 10.2 innings. He would make another 12 starts for the Corpus Christi Hooks before getting the nod to move up to the minors’ final stop: Class AAA. And the string of impressive performances continued. Armenteros made 10 starts with the Fresno Grizzlies in the Pacific Coast League, including six consecutive games in which he fanned at least eight in every start. Overall, the well-built pitching prospect made 24 appearances, including 20 starts, throwing a 123.2 innings with a whopping 146 strikeouts against just 38 free passes. He finished the year with an aggregate 2.04 ERA and a 3.01 FIP.

Projection: Here’s what I wrote about Armenteros in last year’s Handbook when I ranked him as the club’s seventeenth best prospect:

“The data’s rather limited: he threw 61.0 innings in his first stint stateside, and he made three relatively brief stops in his rapid ascension through the minor league ladder. But limited sample size be damned. He’s been flat out impressive. In his longest stint last season – he threw 90.1 innings with Lancaster – he fanned slightly more than 27% of the batters he faced. And because Lancaster is a complete bandbox, his homerun rate spiked. Look for that to regress greatly. He’s primed for a massive, massive breakout in 2017.”

A 2.04 ERA and a double-digit strikeout rate certainly qualify as a massive breakout. So let’s delve deeper: Of Armenteros’ 20 starts, the La Habana, Cuba native fanned 10 hitters twice, nine hitters three times, and eight hitters five times. He had two separate games – a five-inning start in mid May and a four-inning relief appearance a month later – in which he didn’t surrender a hit; and he had three one-hit games of five-plus innings.

As for his overall production, consider the following:

Between 2006 and 2015, there were three 23-year-old pitchers to posted at least a 27.5% strikeout percentage with a walk percentage between 6.5-8.5% in the Texas League (min. 60 IP): Jharel Cotton, Dan Straily, and Mark Worrell. Cotton has the chance to develop into a nice little backend starting pitcher. Straily has been a league average starter. And Worrell briefly got a couple big league cups of coffee.

Now let’s take a look at his production in the Pacific Coast League. Consider the following:

Only one 23-year-old pitcher – Dan Straily – posted at least a 29% strikeout percentage with a walk percentage between 7-9% in the Pacific Coast League (min. 50 IP).

Armenteros, like Straily, has the makings of a nice serviceable #4-type arm.

Ceiling: 2.0- to 2.5-win player

Risk: Low to Moderate

MLB ETA: 2018

6. Cionel Perez, LHP

Background: Hailing from La Habana, Cuba, the organization signed the 5-foot-11, 170-pound southpaw in December 2016 – though it did have a Brady Aiken-type feel to it. The ball club originally had a deal worth $5.15 million in place, but a physical revealed a potential issue with his talented left elbow so the franchise voided the deal. The two sides, unlike the Aiken situation, were able to come back to terms on a deal. This time, though, for just $2 million. Last season, his first in stateside baseball, Perez made stops at three different levels, going from the Midwest League to High Class A and then eventually to the Texas League. In total, the small-ish southpaw tossed a total of 93.2 innings of work, striking out 83 against just 27 walks. He finished the year with an aggregate 4.13 ERA and a 3.22 FIP.

Projection: Perez was particularly dominant in the Cuban National Series between the 2013-14 and 2014-15 seasons – despite being just 17- and 18-years-old. He tossed a total of 139 innings with the Cocodrilos de Matanzas, striking out 100 and walking 61 to go along with a 2.20 ERA. It’s notable because the league is incredibly hitter-friendly and notorious for low punch out rates. Stateside, despite not throwing a meaning pitch in more than a year, Perez showed very little rust. And he responded well to the ball club’s aggressive development schedule. The control, which will likely tick up next season due to the layoff, looks no worse than average and his swing-and-miss ability looks promising. Right now, he looks like a competent future #3/4 with a touch more upside if everything works out. Think pre-injury Derek Holland.

Ceiling: 3.0- to 3.5-win player

Risk: High

MLB ETA: 2018

7. Jairo Solis, RHP

Background: Signed out of the Dominican Republic two years ago. The wiry 6-foot-2, 160-pound right-hander made his anticipated debut in 2017. And it was well worth the wait. Solis, who hails from Puerto Cabello, Venezuela, began the year with six dominant starts in the foreign rookie league. He continued to blow the competition away once he moved stateside to the Gulf Coast League. And he remained nearly unhittable during a late-season promotion up to the advanced rookie league. When the dust had finally cleared, Solis made 15 appearances, 10 of which were starts, throwing 61.1 innings with 69 strikeouts and 21 walks. He finished the year with an aggregate 2.64 ERA and a 3.07 FIP. All at the ripe old age of 17.

Projection: Obviously, the sample size is incredibly limited – just three brief stops in a shortened season. But Solis is one of the most intriguing arms in the minor leagues. He’s lanky and projectable with a strong feel for the strike zone and a promising ability to miss bats. He’s likely punched his ticket to Low Class A. Until then, it’ll be a wait-and-see approach for the high octane teenager.

Ceiling: Too Soon to Tell

Risk: N/A

MLB ETA: N/A

8. Riley Ferrell, RHP

Background: The hard-throwing right-hander was frequently incredible, often times plagued by some consistency issues, during his three-year tenure as Texas Christian’s fireman. Ferrell fanned an incredible 53 hitters in just 31.2 innings of work during his junior year. But his control, which was previously average or better, completely disappeared, forcing him to slide a bit in the 2015 draft. Houston grabbed the 6-foot-2, 200-pound fire-slinger in the third round that year. And after battling those same control issues during his professional debut, Ferrell seemingly righted the ship in 2016. Over his first 10 innings, he struck out 14 and walked just a pair. But an aneurysm in his right shoulder forced him to undergo season-ending surgery. Finally healthy, Ferrell appeared in just two games in High Class A before spending the rest of the season dominating the Texas League. He tossed a combined 54.0 innings, strikeout out 60 and walking just 14.

Projection: Per the usual, here’s what I wrote about the relief artist heading into the 2015 draft:

“Shutdown dominant closer in waiting. And the minor control hiccup this season [should prove to be of no concern because] Ferrell has historically shown better-than-average control. Throw in one of the better fastballs in the draft and he’s primed to move quickly through the minors. In terms of comparable think Nick Burdi.”

Simply put, he’s big league ready. And it would make very little sense for Houston keep him down in the minors. The control, which looked like an above-average skill two years ago, returned with a vengeance last season as well. I would expect him to be working the eighth-inning for Houston by midseason, at the very least.

Ceiling: 1.5-win player

Risk: Low to Moderate

MLB ETA: 2018

9. Brandon Bailey, RHP

Background: In one of the more intriguing trades of the offseason. Division rivals Houston and Oakland got together for a classic one-for-one challenge trade in late November, agreeing to send Brandon Bailey to the Astros for Ramon Laureano. From Houston’s point of view the trade was necessitated in an effort to clear up some of the logjam surrounding the club’s 40-man roster. And it was a win. Oakland originally grabbed the diminutive right-hander out of Gonzaga University in the sixth round two years ago after a dominant junior campaign. The generously listed 5-foot-10, 175-pound righty tossed 100.1 innings for Bulldogs’ Head Coach Mark Machtolf, recording an impressive 125 punch outs against just 31 base-on-balls. Bailey continued to dominate during his professional debut as well, posting a 46-to-10 strikeout-to-walk ratio in 43.0 innings between the Arizona Summer and New York-Penn Leagues. Last season he split time between the Midwest and California Leagues, throwing 91.0 innings with a whopping 120 strikeouts and just 31 walks. He finished the year with an aggregate 3.26 ERA and a 3.31 FIP.

Projection: Love it. Love it. Love it. The recently-traded Laureano was coming off of a horrendous showing in the Texas League, hitting .227/.298/.369 and essentially had no future in Houston thanks to a glut of outfielders at both the major and minor league levels. Bailey, on the other hand, is an incredibly intriguing, often times dominant minor league arm – though one not without red flags. The tiny righty underwent Tommy John surgery during his high school career and he’s going to always have to over-perform to cast away any doubts about his frame size. As for the production, consider the following:

Between 2006 and 2014, there were only five 22-year-old pitchers to post a 30% strikeout percentage with a walk percentage between 8-10% in the Midwest League (min. 50 IP): Zack Weiss, Zach Herr, Jade Todd, Ryan Aldridge, and Andrew Taylor. Weiss, the most interesting name, has a chance to develop into a serviceable MLB reliever.

Obviously it’s not incredibly encouraging. So let’s take a look at his work in the California League. Consider the following:

Between 2006 and 2014, there were only three 22-year-old pitchers to post a 30% strikeout percentage with a walk percentage between 6-8% in the California League (min. 25 IP): Steven Okert, Steve Geltz, and James McDonald – three solid big league arms.

Bailey will likely be given the opportunity to start, especially if he continues to miss a plus amount of bats. There’s some backend starting material here. But it wouldn’t be surprising to see him develop into the right-handed version of Tim Collins.

Ceiling: 1.5- to 2.0-win player

Risk: Moderate to High

MLB ETA: 2019

Background: A consistent, often times dominant, performer throughout his four-year minor league career. Davis has never finished a minor league season with a wRC+ mark below 134. And last season was much the same. A two-way player at Cal State Fullerton, Davis – despite borderline dominant numbers in the Texas League two years ago – opened the 2017 campaign back with Corpus Christi. In 87 games with the Hooks, the 6-foot-3, 225-pound third baseman slugged an impressive .279/.340/.510 with 18 doubles and 21 homeruns in just 87 games of action. Houston finally relented and sent him up to Class AAA in mid-July, though that assignment lasted all of just 16 games before he got the call from the parent company. Davis finished his minor league season with an aggregate .282/.345/.527 triple-slash line with 23 doubles and a career high-tying 26 homeruns. His overall production, according to Weighted Runs Created Plus, topped the league average mark by 36%. His MLB numbers: despite a low batting average, Davis, who batted .226/.279/.484, produced at the league average equivalent.

Projection: Here’s what I wrote about him in last year’s Handbook when I ranked him as Houston’s 12th best minor league prospect:

Well, it’s taken a couple years but I’m officially convinced of the wallop he’s packing in his bat. Davis is showing a solid-average eye at the plate, above-average power, but his swing tends to get a bit long resulting in his swing-and-miss tendencies. One gets the feeling he’s a poor man’s Kris Bryant, one capable of putting together a .240/.320/.440-type line with 17- to 20-homeruns. He’s an atrocious third baseman, so I’d expect a move across the diamond and/or into a DH role.”

That initial projection, by the way, wasn’t too far off from his actual debut triple-slash line. So let’s update this a bit, shall we? First, consider the following:

Between 2006 and 2015, here’s the list of 24-year-old hitters to post a 130-140 wRC+ and at least a .200 ISO in the Texas League (min. 300 PA): Joe Koshansky, Andrew Brown, Chris McGuiness, Brandon Boggs, and Blake Tekotte. The two most successful big league hitters of the group – Brown and Boggs – were terrible.

So let’s re-examine his work in 2016. Consider the following:

Between 2006 and 2015, here’s the list of 23-year-old hitters to post a 130-140 wRC+ and at least a .200 ISO in the Texas League (min. 300 PA): Kyle Parker, Telvin Nash, Josh Rutledge, and Tim Wheeler. Again, it’s a completely underwhelming group of performers.

As for his defense, according to Clay Davenport’s metrics, he was – more or less – average last season. Ultimately, Davis is going to be a starting third baseman for a non-contending team, sort of like a poor man’s version of Kris Bryant, just like I wrote in last year’s Handbook.

Ceiling: 1.5-win player

Risk: Moderate

MLB ETA: Debuted in 2017

Author’s Note: All statistics mentioned were gathered from Baseball Reference, FanGraphs, ClayDavenport.com, or Baseball Prospectus.