by Eric Stashin (aka The Rotoprofessor)

Which prospects are on the verge of making an impact in the Major Leagues? This weekly column will rank the ten who are closest (as well as other names that are being closely considered). Keep in mind that while talent is factored in opportunity plays a major role, so there may be some “lesser” prospects who rank fairly highly on the list (ITC = In the Conversation; NR = Not Ranked):

1) Nick Castellanos – Detroit Tigers – Outfielder (1)

2013 Minor League Statistics – .296, 11 HR, 43 RBI, 59 R, 3 SB over 334 AB

Andy Dirks continues to struggle and the Tigers suddenly find themselves in a dog fight in the AL Central. They seem like a team that is need of a spark and you would think Castellanos has the potential to provide that. Already with 27 doubles and a .482 SLG, he should provide an instant boost to the bottom of the order. It’s just a matter of when the Tigers decide to give him his chance

2) Carlos Martinez – St. Louis Cardinals – Starting Pitcher (2)

2013 Minor League Statistics – 3-2, 2.09 ERA, 43 K, 13 BB over 47.1 IP

Being stretched back out as a starting pitcher at Triple-A, Martinez has shown lights out stuff thus far. He’s showing an ability to generate groundballs (1.68 GO/AO) and clearly has the ability to show good control while missing bats (he has hit a little slide, with 3+ BB in two of his past three starts). He also threw 104.1 innings last season, so an innings cap may not be a major issue as he currently stands at 55.1 innings. That means 80-90 innings left, more than enough to get him close to the end of the season. With Major League experience in the bullpen, the Cardinals may want to utilize those innings in the Majors as they are in a battle in the NL Central. With Joe Kelly all that is standing in his way, look for an arrival shortly after the All-Star game, if not sooner.

3) Tyler Skaggs – Arizona Diamondbacks – Starting Pitcher (NR)

2013 Minor League Statistics – 6-6, 4.26 ERA, 87 K, 28 BB over 76.0 IP

He’s had some problems in the Pacific Coast League (4.26 ERA), but at least some of that is based on luck with a .346 BABIP (despite an 18.5% line drive rate). He hasn’t been beaten by the long ball (4 HR) and has shown good strikeout and walk rates. With Trevor Cahill hitting the DL, Skaggs should get an extended look to fill the void.

4) Taijuan Walker – Seattle Mariners – Starting Pitcher (3)

2013 Minor League Statistics – 6-7, 2.18 ERA, 108 K, 34 BB over 95.0 IP

Erasmo Ramirez may be the first in line and Danny Hultzen has returned to the mound. That said, his recent promotion to Triple-A hasn’t phased him (2-0, 0 ER, 5 H, 4 BB, 12 K over 11.0 IP). After a few more starts like this, the Mariners may not have a choice but to get his feet wet in the Majors. They have shown this season that once a prospect proves himself they are willing to promote him, so it shouldn’t be too much longer.

5) Cesar Puello – New York Mets – Outfielder

2013 Minor League Statistics – .331, 15 HR, 55 RBI, 51 R, 18 SB over 236 AB

Marlon Byrd has been fantastic, but is anyone willing to guarantee that he’ll be a member of the New York Mets a month from now? While Eric Young should continue to see playing time for the presence he offers atop the order, there is little else in the outfield. Juan Lagares? Kirk Nieuwenhuis? Andrew Brown? Heck, even Lucas Duda at this point? Puello has raked at Double-A and the Mets need to see if he could be a piece for the future or not. He’s going to get a chance, and it should come once the trade deadline dust settles.

6) Sonny Gray – Oakland Athletics – Starting Pitcher

2013 Minor League Statistics – 7-5, 3.02 ERA, 98 K, 32 BB over 95.1 IP

The back of the A’s rotation continues to be filled with question marks (like the hamstring injury to Jarrod Parker), while Gray had been pitching well at Triple-A. Had is the key word, because he’s hit a bit of a rough patch of late (11 ER over 19.0 IP). He’s going to get an opportunity, but it no longer feels imminent.

7) Grant Green – Oakland Athletics – Second Baseman (NR)

2013 Minor League Statistics – .317, 11 HR, 49 RBI, 60 R, 4 SB over 334 AB

The question with Green is going to be when his opportunity comes, because the A’s do have alternatives available to them. Green is trying to force their hand, however, and while you can argue that the numbers are a bit inflated (.368 BABIP, 19.1% line drive rate entering play yesterday) he deserves a shot and there is an obvious need (0 HR, 4 SB from their 2B). Is Eric Sogard really the answer? The question is if the team decides to give a retread like Jemile Weeks an opportunity before Green.

8) Xander Bogaerts – Boston Red Sox – Shortstop (4)

2013 Minor League Statistics – .297, 10 HR, 46 RBI, 50 R, 7 SB over 286 AB

With Will Middlebrooks performing well at Triple-A, the thought of rushing Bogaerts to the Majors should subside at least a little bit. That said, he’s no guarantee when he returns to Boston and, unless the team acquires a piece for the left side of the infield via trade, the Red Sox could hope Bogaerts offers them a Manny Machado like spark.

9) Josh Phegley – Chicago White Sox – Catcher (8)

2013 Minor League Statistics – .316, 14 HR, 40 RBI, 38 R, 1 SB over 228 AB

The White Sox appear primed to tear everything down and start from scratch. While Tyler Flowers may not get traded, he shouldn’t stand in the way of seeing if Phegley can be an option for them moving forward. While he hasn’t been good previously, he’s continued to produce in 2013 and could make a Geovany Soto type impact later in the year. That should put him on all deeper fantasy league radars.

10) Wilmer Flores – New York Mets – Second Baseman (NR)

2013 Minor League Statistics – .320, 10 HR, 64 RBI, 53 R, 1 SB over 325 AB

He has been scorching hot, including hitting .342 with 6 HR and 25 RBI in June (51 RBI since May 1). He may not have tremendous power, yet, but he has a .508 SLG thanks to 25 doubles. The question really is where he’ll play, with Daniel Murphy at 2B, but for a team like the Mets they need to figure out a way to squeeze him into the lineup. If there was a clear path for him in the Majors, he would find himself significantly higher on this list.

In The Conversation:

Jarred Cosart – Houston Astros – Starting Pitcher (ITC)

Control is the issue, as he’s walked 46 batters over 87.2 IP at Triple-A this season. If he can get that under control, the sky appears to be the limit as he’s shown the ability to generate swings and misses (90 K) and groundballs (2.47 GO/AO).

Billy Hamilton – Cincinnati Reds – Outfielder (ITC)

He just can’t seem to find his footing at Triple-A and, the longer this goes on, the more and more likely it is that he’s nothing more than a pinch runner come September. Would anyone have predicted that prior to the season?

Danny Hultzen – Seattle Mariners – Starting Pitcher (NR)

He’s back from injury, the question is how far on the depth chart he is (possibly behind Erasmo Ramirez and Taijuan Walker). He should debut this season, as long as he’s healthy, it’s just a matter of when.

Erik Johnson – Chicago White Sox – Starting Pitcher (ITC)

While he struggled with his control in his first Triple-A outing, he looked just fine in the second (2 ER over 7.0 IP) and now owns a 2.21 ERA, 87 K and 27 BB over 16 starts. Even if Jake Peavy isn’t traded Johnson should at least get a trial run (only 92.1 IP in 2012 means an innings limit).

Jimmy Nelson – Milwaukee Brewers – Starting Pitcher (ITC)

Can he solve his control at Triple-A? That’s the question, with 15 BB over 20.1 IP (though he only walked 2 batters over 5.1 innings in his last outing). Overall he has 91 K, 30 BB and a 1.67 GO/AO over 89.1 IP this season and the Brewers have huge needs in the rotation. It’s only a matter of time.

Miguel Sano – Minnesota Twins – Third Baseman (ITC)

He continues to rake (.303, 22 HR, 64 RBI overall), though chances are he won’t debut until September, if at all. That said, he is one of the premier prospects in the game and should be in all Top 5 lists entering 2014.

Jonathan Singleton – Houston Astros – First Baseman (10)

We all know about Singleton, his power potential and his 50 game suspension to open the season. Could he have already been in the Majors had he not missed time? Possibly, but not if he was playing like he currently is. The power hasn’t been there yet, despite calling the PCL home and, until that happens, he’s going to continue marinating at Triple-A.

George Springer – Houston Astros – Outfielder (ITC)

Springer has shown his full skillset since joining Triple-A, but he also has continues to strikeout at an alarming rate. While that may not matter to the Astros (the team with the most strikeouts in the Majors), they also have shown tremendous patience with all their prospects of late. He brings 30/30 upside, though with the potential to hit .250ish or worse, when he finally arrives later this season.

Jonathan Villar – Houston Astros – Shortstop (ITC)

The fact that Jake Elmore was promoted ahead of him speaks volumes at this point (explaining why Villar has fallen from our Top 3). While he should still get an opportunity at some point, it may not be until September (barring a trade of Jose Altuve).

Michael Wacha – St. Louis Cardinals – Starting Pitcher (ITC)

The Cardinals gave him some time off to conserve his innings, though he returned to the mound last night. That said, he likely has fallen behind Carlos Martinez on the depth chart so it may be a while before he’s back in the Majors.

Graduated:

Brad Miller – Seattle Mariners – Shortstop (7)

Injured:

Oscar Taveras – St. Louis Cardinals – Outfielder

Travis d’Arnaud – New York Mets – Catcher

Christian Yelich – Miami Marlins – Outfielder (currently rehabbing)

Dropped Off The List:

Hunter Morris – Milwaukee Brewers – First Baseman

Jake Marisnick – Florida Marlins – Outfielder