At last weekend’s Saber Seminar, Red Sox senior baseball analyst Tom Tippett displayed this cryptic image of an undisclosed player’s performance, as measured by an undisclosed metric, through the first 30 games of the 2013 season:

This snapshot tells us something about past events, but nothing about what will happen next. The crucial piece of information about any player whose performance has sunk or risen sharply is what the following section of squiggly line looks like. In many cases, of course, players eventually find their forecasted levels, as Tippett’s mystery man did over a full season (the blue line represents the level at which the Red Sox had projected him to perform):

People who work for teams, though, don’t have the luxury of assuming that every deviation is the result of random variation, even though that’s often the answer. Recognizing a real change quickly can be the difference between winning the division and settling for a wild card — or worse, between earning a wild card and heading home empty-handed. Being overly reactive can be just as dangerous, however. Tippett also displayed the following image, a moving average of the player’s 10 most recent games (the green line represents league average):

Over the course of a season, a player’s performance might have several peaks and troughs that could convince an overzealous observer to celebrate prematurely or sound a false alarm. And the risk of making the wrong call, or the reward of making the right one, is never higher than at the beginning of a player’s career, when we’re the least confident that we know what we’re seeing.

In late January, Baseball Prospectus lead prospect writer Jason Parks released his list of the top 101 prospects in baseball. Thirty-two of those 101 (complete list here) have played in the majors this season, and most of those major leaguers have lost their rookie eligibility. From this point forward, we can’t call them prospects. They’re just players — young, yes, and probably promising, but expected to produce in the present, not in the nebulous future where their productive years used to reside.

All these players did enough right to earn a big league audition, but their paths have since diverged. Some are off to strong starts. Others have faltered. If we created a graph like Tippett’s of each player’s performance, but made the x-axis the length of a career instead of a season, the trend line representing each of these 32 players’ showings in 2014 would barely be visible. Absent that context, it can be very easy to read too much into early returns. In a few cases, though, the small samples loom large, as exposure to elite competition reveals weaknesses that might have been hidden at lower levels.

In cases like these, when the plate appearance or innings pitched totals are too low for publicly available projections to have budged by much, it’s often illuminating to see how the industry perception of a player has changed. To find out which recent top prospects have helped or hurt their causes, I surveyed 15 scouts, pro scouting directors, statistical analysts, and other front-office executives whose value to their teams stems in part from their ability to spot changes in true talent before bigger samples make those shifts obvious to everyone. I sent them the list of the 32 preseason top prospects who’ve accrued some major league service time, and I asked them to tell me (via email) which five had changed their minds for the better and which five had changed their minds for the worse since spring training.

All the respondents started the season with different expectations for each of these players, so the point wasn’t to see which players they liked best or least, or even how they thought the players stacked up relative to each other. Nor was it to see which players have over- or underperformed their projections so far, which we could determine with statistics alone. The goal was to pinpoint the players who’ve done something to either raise long-term expectations or make informed observers more bearish about their futures. Not all the respondents had seen or studied every player closely enough to have an opinion on all 32, and not all sent me five names in each category, but as the ballots came back, some patterns emerged. Let’s take a spin through the most popular picks, covering both the good and the bad.

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Marcus Stroman, RHP, Blue Jays: Stroman made his pro debut out of the bullpen after signing with Toronto following the 2012 draft, then transitioned to the rotation in Double- and Triple-A. Even so, some evaluators didn’t expect him to stick in a starting role. Scouts operate by building a mental database of players who’ve succeeded before, then looking for the same attributes in others. Stroman’s stuff earned him believers, but his 5-foot-9 frame made it difficult to come up with comps.

Following the same script he had in the minors, Stroman made his major league debut in relief in early May, but his big league bullpen career lasted only 10 days. After a brief return to the minors, he switched to a starting role with the Jays on May 31, becoming the first pitcher listed under 5-foot-10 to make a start in the majors since Fabio Castro made one (and only one) for the Phillies in 2007. The other sub-5-10 starters of the 21st century (Shane Komine, Michael Tejera, Arnie Munoz, and Daniel Garibay) were just as forgettable, so Stroman has already accomplished something special merely by making 14 starts.

Judging by his results so far, he’s going to make many more. While he’s been knocked out of a few starts early (including recording only two outs in his most recent start), he’s also shown the ability to go deep into games (including shutting down Detroit for nine innings earlier this month). He’s thrown strikes, gotten ground balls, and held his own against left-handed hitters, limiting opponents to an overall .226/.278/.316 line despite making more than half his starts in the Rogers Centre.

“[I] thought he was more likely to be an 8th inning set-up type or bottom of the rotation starter,” wrote one front-office type. “Thus far, he has proved capable of being a mid-rotation type.”

Said one scout who put Stroman on his list of positive surprises: “I was worried about the lack of an out pitch vs. LHHs, although I did think he’d be able to stick as a starter. The development of his cutter and fastball command have essentially molded him into a pitcher with three plus offerings.”

For now, at least, the talk about how Stroman is too short has subsided.

“I hope nobody mentions again how he should be a bullpen type just because of his frame,” another scout said.

Billy Hamilton, CF, Reds: Hamilton was the closest equivalent to Stroman among position-player prospects this spring. His elite speed was as flashy a skill as Stroman’s mid-90s fastball, but scouts’ enthusiasm was tempered by concerns about Hamilton’s strength and physique. He managed only a .308 on-base percentage and an .087 ISO for Triple-A Louisville last season, and the pessimist’s preseason narrative was that he’d lack the strength to punish pitchers when they pounded the zone.

Those fears seemed justified when Hamilton had a sub-.200 OBP on April 15, but he’s posted an above-league-average .281/.311/.408 line since then, and on the season he’s equaled his minor league single-year home run high (6) and set a new personal doubles record (24). That’s still not the sort of OBP teams look for from a leadoff man, but for a plus center fielder with elite legs, average offense is a springboard to stardom.

“[Hamilton’s] OBP is low and his CS are high, but he showed more contact and power than expected, and if he can be a 95 OPS+ guy (like he has been so far), his fielding and running will make him an above average player for a long time,” wrote one evaluator. “Call him a 3 to 4 win player if this is what he is. And that’s way better than I thought he would be. I honestly thought he wouldn’t hit and would turn into a defensive replacement/pinch runner.”

Admitted an NL scout: “I thought he was more of a smoke and mirrors prospect with blazing speed and limited hitting ability. After watching a good amount of his games this year, he has shown the ability to consistently square the ball up. … My expectations for him next year will be much higher.”

Gregory Polanco, RF, Pirates: Polanco found himself at the center of controversy, as the Pirates, appearing to put service time ahead of performance, delayed his promotion until June 10 despite their offensive struggles in right field and Polanco’s hot hitting for Triple-A Indianapolis. The 22-year-old’s .244/.311/.354 major league line after two-plus months isn’t quite what Pirates fans envisioned when they called for his promotion, but while Polanco’s power has been missing so far, he hasn’t looked overmatched. His swing, chase, and strikeout rates are well below league average, and the more pitches he sees, the more contact he makes.

“Polanco has shown better plate discipline than I expected for a young hitter,” said one respondent. “I think the power will continue to come and he’ll be a 20 HR/20 SB guy with a high OBP.”

Jake Odorizzi, RHP, Rays: Even in a lost season for Wil Myers, the Rays have gotten significant value from the James Shields trade thanks to Odorizzi’s performance, which one scout termed a “huge breakthrough.”

“Odorizzi could always pitch and he always had a deep arsenal, but the knock on him was always the lack of that put-away pitch,” another scout wrote. “Now we’re looking at a dude who strikes out hitters left and right with an upper 80s, low 90s fastball. The key for him has been the development of that changeup, and I think he’s done a better job of learning how to use it as the year has progressed. He really pitches well with the fastball and uses that cut-slider and lollipop curve to disrupt timing while putting away hitters with a sneaky fastball or change.”

Odorizzi’s refined changeup is really a new pitch, a splitter he learned from Alex Cobb. He’s using it more often than he used to throw the change, and while it’s not the weapon Cobb’s splitter is, it’s a far more effective pitch than Odorizzi’s old off-speed offering.

One rival scouting director, who noted that many of the 32 preseason top prospects still have MLB “sample sizes that are simply too small to fairly evaluate,” wrote that “Odorizzi is the only player on the list that has really surpassed what we would have expected in a rookie campaign … his K-rate is far better than we could have predicted.”

“He was going to be a pitchability guy, but he is now hinting at more than that,” said a third scout. “From back-end to number 3, or perhaps even better.”

Arismendy Alcantara, CF, Cubs: Alcantara became the first of the Cubs’ cresting wave of young position players to graduate from the minors, debuting at second base on July 9 and shifting to center when Javier Baez arrived. Although he hasn’t hit yet, Alcantara’s experience at four defensive positions (second, short, third, and center) will help keep him on the field as Chicago shoehorns its higher-ceiling sluggers into the lineup.

“I think he’ll hit enough to play every day, and he’s going to have enough versatility to play in multiple positions,” one scout said. “He might even play well at multiple positions. I saw him at second base in Iowa, but the limited looks I’ve seen on TV in center field look solid. There’s some sneaky pop in there that has a chance to play in the majors. … He will need to tighten the approach, though. He swung at everything when I saw him in AAA this year.”

Although he’s had contact issues, Alcantara has swung less often and chased no more often than the typical major leaguer, so he’s not nearly in the swing rate stratosphere of Javier Baez, the power prospect who recently displaced him at second.

Chris Owings, SS, Diamondbacks: Before hitting the DL with a shoulder injury at the end of June, Owings hadn’t done anything flashy in his first full season, but he’d been above average with the bat and at least average on defense, propelling him past Didi Gregorius and Nick Ahmed (both of whom are slightly older than Owings) on Arizona’s shortstop depth chart.

“Looks like an everyday MLB SS,” a scouting director said simply.

Another scout offered more glowing praise: “Above average everyday regular as a SS,” he said. “Those are precious and rare. I liked him, but it looks like he’ll be a tick better than expected.”

George Springer, RF, Astros: Through his first 15 games, Springer hit .180/.254/.213 with a 34 percent strikeout rate, prompting some to wonder whether he’d been called up too soon. Springer’s strikeout rate has dropped only slightly since then, but he’s paired the K’s with patience and power, posting the third-highest ISO of any hitter with at least 200 plate appearances since May 2 (behind only Edwin Encarnacion and Houston teammate Chris Carter).

“Springer is going to swing and miss, but I have been impressed by the way he has made adjustments to pitchers later in games,” wrote one assistant GM. “He’s hit for a ton of power in a very short time and it looks like he was wise to turn down that contract extension.”

Added a front-office type: “There is some uncertainty with guys who swing and miss and strikeout a lot at the minor league level and how that translates to the big leagues. Many of those guys who swing and miss in the minors, nosedive in the big league and become 4-A players. But for Springer, the power plays.”

Also receiving multiple up votes: Yordano Ventura (Royals), Aaron Sanchez (Blue Jays)

Conspicuously scarce: Javier Baez, 2B, Cubs. Despite posting a batting line and plate discipline stats unlike any other major leaguer’s, Baez didn’t show up on anyone’s list. No one was expecting him to have a typical profile, and so no one has been surprised by his early results. “If he hits 50 HR’s and has a 30+% K% in a season, it wouldn’t surprise me at all,” one scout said. “I think he’s the most fun hitter to watch in possibly all of baseball.”

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Jackie Bradley Jr., CF, Red Sox: Yeah, you knew this was coming. Bradley recorded a .216/.288/.290 slash line in close to 400 plate appearances and just got sent back to Triple-A, so there was no way he wouldn’t appear here. In almost 500 combined plate appearances in the majors across two seasons, Bradley has shown little of the patience and power that made him a highly rated prospect, and at 24, he doesn’t have a leash as long as scuffling 21-year-old teammate Xander Bogaerts.

“He’s swinging at 29% of pitches out of the strike zone this year at the major league level,” one analyst said. “That is a drastic increase from what he was doing at AAA. One would expect that chase percentage should rise when moving from AAA to the majors, but his increase is much larger than normal and chase percentage stabilizes fairly quickly.”

“I still want to believe the bat is better than this, and I do because of his instincts and approach, but this has been very disappointing,” a scouting director said.

A scout summed up Bradley’s future: “The swing plane isn’t conducive to hitting with power, and he hasn’t wowed with any sort of impactful baserunning ability. He’d better be REALLY good in center field.”

Bradley has been excellent defensively, ranking second among center fielders (behind Juan Lagares) in both DRS and UZR, but his prospect status was partly tied to his bat. If the Sox don’t straighten out that aspect of his game, they’ll have to settle for the second coming of Endy Chavez.

Erik Johnson, RHP, White Sox: It took five starts for Johnson to lose his spot on the major league roster, and 20 more in the minors for him to be placed on the Triple-A disabled list last week with what the White Sox called “shoulder fatigue.” Injury is one possible explanation for why Johnson’s fastball has dropped two ticks and his peripherals have gone the wrong way. (He’s walked 69 in 129.1 innings, with only 81 strikeouts.) Even if Johnson’s shoulder isn’t the root cause of his catastrophic season, he could use a mercy stint on the DL.

“The stuff has been down across the board and, as of my last look, he’d turned himself into almost solely a fastball/slider machine with decreased velo, and the command is way down,” one scout reported. “The athleticism was really poor for me on my last look and caused red flags. There just isn’t much margin for error right now. Definitely more of a power look last year with four usable pitches.”

Concluded another scout: “It’s alarming, and he hasn’t looked like a major leaguer.”

Michael Choice, OF, Rangers: Billy Beane’s strategy of trading top prospects for veteran talent hasn’t come back to bite him here: Former Oakland outfielder Choice is one of the few current Rangers who hasn’t suffered an injury, but Texas might have been better off if he had. Playing all three outfield spots with an occasional start at DH, Choice hit .177/.247/.318 until his demotion in early July, giving him the sixth-lowest wRC+ of any hitter with at least 200 plate appearances this season. His bat hasn’t really rebounded in Round Rock.

“There’s still a chance to be a solid everyday guy, because the tools are still there,” one scout said. “It’s fantastic bat speed and raw power, but there’s a little more doubt for me. It doesn’t appear that he’s handled failure very well, as the approach has sort of deteriorated and he’s fallen into some bad habits with his swing. I wouldn’t give up on him yet, but the arrow is most definitely down. He looks like he needs the offseason and a reset button.”

Another evaluator was more blunt: “He is almost 25, has been poor in the PCL, hasn’t done a thing in the big leagues,” he said. “Can’t hit, can’t field. Is he anything more than a platoon up and down guy going forward?”

Oscar Taveras, RF, Cardinals: Taveras made it onto roughly a third of the downgrade lists — a lower percentage than Bradley, Choice, or Johnson, but a higher percentage than anyone after that. However, he was the last player included on multiple lists, and no one was moved to include a comment about him, which suggests that the concerns weren’t very serious. Still, the slash line is unsightly. Taveras has had to deal with a sporadic schedule of starts, but his ground ball/popup–heavy performance at the plate (combined with shaky defense) hasn’t made a convincing case for more playing time. A flurry of hits immediately after the trade deadline generated some excitement, but he’s since sunk back into a slump.

Also receiving multiple down votes: Christian Bethancourt (Braves), Eddie Butler (Rockies), Garin Cecchini (Red Sox), Jon Singleton (Astros)

Conspicuously scarce: Xander Bogaerts (Red Sox) and Taijuan Walker (Mariners). Bogaerts, the consensus spring favorite for AL Rookie of the Year in the wake of his preternaturally polished appearance during Boston’s 2013 playoff run, has been a replacement-level player for the Red Sox this season, but only two respondents — one of whom noted that he “still has loads of talent” — included him on their lists of downgrade guys. Bogaerts’s youth excuses his struggles, so few evaluators have soured on his future as a result of his rookie year.

Walker also appeared on only two lists, which is somewhat more surprising, given that he was expected to start the year in Seattle but didn’t make his season debut for the Mariners until late June. Walker appears to have recovered from the shoulder inflammation that sidelined him early on, which is one reason for optimism, but he’s back in the minors. Either the evaluators I contacted don’t think the 22-year-old’s disappointing season has any implications for his future, or they weren’t high on him from the start.

Mixed Feelings

If you found yourself disagreeing with one or more of the above judgments, you’re not necessarily wrong. In a few cases, the team employees I contacted disagreed with each other so strongly about what we’ve learned from a particular player’s season that one rated the player a disappointment while another deemed him a pleasant surprise. Player evaluation is hard! The following three players received at least one up vote and one down vote.

Nick Castellanos, 3B, Tigers

Pro: “I might have been a bit lower than most on Castellanos coming into the spring. … I didn’t see any standout, impact-type tools, and he might prove me wrong. He shows a veteran calmness at the plate and is a line drive-hitting machine. A guy like Castellanos, who has good raw power and athleticism, could maintain a high BABIP given his propensity to hit line drives at the rate he does.”

Con: “His glove has been beyond atrocious at 3B and it will negate most of his value. I think it’s better to try to move him to LF. … I can’t see him becoming an above average regular at 3B, simply because of his fielding. If he moves, his outlook might change again to positive, but right now, nope. And again, it has nothing to do with his bat.”

Andrew Heaney, LHP, Marlins

Pro: “I think he has raised the floor for me. He really commands his stuff in and out of the zone. The breaking ball still isn’t better than average for me, but it’s got more depth than last year.”

Con: “Heaney has softer stuff and he has to be perfect in order to be successful. I just didn’t see enough weapons and he doesn’t yet have the command or pitchability to make a difference at the highest level.”

James Paxton, LHP, Mariners

Pro: “I saw him bad in AAA last year. The velocity was all over the place and he was battling his delivery the entire game. Didn’t show any curveball command and was even toying with a cutter at that point. He’s been a different dude ever since he stepped on to a big-league diamond. Obviously tall lefties who touch the upper 90s don’t grow on trees. I think he’s figured it out and made the strides necessary to become a legitimately solid big-league starter.”

Con: “At first glance, there’s a ton to like. Big lefty, clean arm, deceptive, big velocity. But he doesn’t strike hitters out and gives up a lot of hits. And he’ll be 26 years old in November. He has an unsustainably low career BABIP against him in his small sample in the big leagues as well.”

Also appearing on both lists: Kevin Gausman (Orioles), Rougned Odor (Rangers), Aaron Sanchez (Blue Jays)