AAA

Jason Berken, RHP, Lehigh Valley IronPigs (Philadelphia Phillies)

Season: 11 GP (4 GS), 42.1 IP, 3-2, 3.89 ERA, 1.39 WHIP, 2.8 BB/9, 6.7 K/9

May: 6 GP (3 GS), 23.1 IP, 2-1, 1.93 ERA, 1.29 WHIP

Berken’s role has fluctuated between spot starter and long reliever this season. After a month’s worth of struggle in April, the veteran right-hander found success in May. His ERA dropped sharply as he threw more innings. In four starts, Berken is 2-0, and he has now started in consecutive appearances. Those two outings saw Berken throw 11 innings and allow only one earned run on nine hits and three walks. It seems unlikely Berken will be called up this year, but more days like these could push the Phillies to try him in the big leagues for the first time since 2012.

Tyler Colvin, OF, Charlotte Knights (Chicago White Sox)

Season: 16 GP, .228/.254/.351, HR, 4 RBI, 6 R, 2 BB, 15 K

May: 16 GP, .228/.254/.351, HR, 4 RBI, 6 R, 2 BB, 15 K

Colvin opted out of his contract with the Miami Marlins right before Opening Day and remained without one into early May. He signed with the White Sox, who shipped him down to Charlotte. Predictably, Colvin took some time to knock off the cobwebs, and his OPS right now would be a career low. However, the outfielder had multiple hits in three of five games to end the month. The White Sox have a few injury concerns in the outfield, so if Colvin can pick it up, he could see some showtime in the bigs this season.

Chris Dwyer, LHP, Omaha Storm Chasers (Kansas City Royals)

Season: 12 GP (2 GS), 24 IP, 0-0, 4.12 ERA, 2.08 WHIP, 8.6 BB/9, 7.5 K/9

May: 7 GP (2 GS), 13.1 IP, 0-0, 6.75 ERA, 2.10 WHIP

Dwyer is nothing more than a long arm for Omaha this season. His high WHIP has been accompanied by a higher ERA recently after an unsustainable run in April. Dwyer has made a pair of spot starts, but he has yet to throw more than 3.1 innings all season long. He appears cemented as a fixture at AAA with a low probability of being added to the big-league roster this year.

Mike Freeman, UTIL, Reno Aces (Arizona Diamondbacks)

Season: 42 GP, .324/.373/.426, 2 HR, 18 RBI, 31 R, 5-5 SB, 11 BB, 24 K

May: 26 GP, .365/.404/.448, 15 RBI, 21 R, 4-4 SB, 7 BB, 15 K

Freeman has been flat out raking this month. He has become one of the hottest hitters out west, and he has done it without hitting a single ball over the fence. At one point in May, he carried a nine-game hitting streak that included four multi-hit games. Freeman jumped from AA to AAA last season, and if his production continues to rise, the perpetually rebuilding Diamondbacks may be forced to give him a shot soon. Defensively, Freeman has spent time at both middle infield positions and all over the outfield, so his versatility might also give him a leg up on the competition.

Kyle Parker, 1B/OF, Albuquerque Isotopes (Colorado Rockies)

Season: 45 GP, .254/.296/.414, 6 HR, 26 RBI, 23 R, 4-5 SB, 10 BB, 50 K

May: 26 GP, .327/.340/.510, 4 HR, 17 RBI, 18 R, 1-2 SB, 2 BB, 26 K

Until May 12, Parker’s season was laughably bad. He was striking out a ton, he was making weak contact, and he wasn’t taking walks. Since that point, however, Parker has experienced a gigantic surge. He hit safely in 16 of his final 18 games in May and improved his once-sagging batting average up above .250. The power is there, as it always has been, and Parker continues to strike out at an exorbitant rate (albeit not as exorbitant as his nearly 40 percent K-rate from April). It looked unlikely that Parker would factor on the Rockies’ big-league club in 2015, but he has postured himself well with this flourish over the past three weeks.

Richie Shaffer, 3B, Durham Bulls (Tampa Bay Rays)

Season: 46 GP, .271/.367/.512, 10 HR, 32 RBI, 28 R, 3-3 SB, 26 BB, 56 K

May: 26 GP, .269/.352/.516, 5 HR, 23 RBI, 15 R, 3-3 SB, 12 BB, 30 K

Shaffer was playing so well at AA Montgomery that the Rays have already promoted him to AAA. In his May 24 debut for the Bulls, Shaffer had four hits, including a pair of homers. He now has three home runs in seven games in Durham and continues to provide an attractive late-season call-up option for Tampa. Shaffer’s .262 batting average at AA wasn’t overwhelming, but his run-production has been outstanding all season long. With seven hits in 21 at-bats already, expect Shaffer to continue swinging a hot bat, and expect him to be a candidate to make his MLB debut in August or September.

AA

Will Lamb, LHP, Frisco RoughRiders (Texas Rangers)

Season: 19 GP, 23 IP, 1-1, 3.13 ERA, 1.39 WHIP, 5.0 BB/9, 8.6 K/9

May: 13 GP, 13 IP, 1-1, 4.85 ERA, 1.77 WHIP

Lamb went through a bit of a rough patch at the beginning of May, giving up five earned runs in his first five appearances. The lefty specialist has turned things around, however, and will ride a five-game scoreless streak into June. Given the way the Rangers’ pitching staff has been snake-bitten with injuries over the past couple of seasons, don’t be surprised if Lamb gets called up a level at some point. He strikes out around a batter per inning and can get guys out from the left side, two qualities that always endear a pitcher to his organization.

Phil Pohl, C, Midland RockHounds (Oakland Athletics)

Season: 4 GP, .250 (2-8)/.333/.375, 2 RBI, R, 2 K

May: 3 GP, .286 (2-7)/.375/.429, 2 RBI, R, 2 K

Pohl appears locked in as the third catcher at Midland at the moment. That’s not a good thing for his playing time. Pohl’s last action came on May 20, even then, it was only his third appearance in May after a lone pinch hit appearance in April. Pohl still appears to be considered an option for the A’s brass, but the organization’s considerable healthy depth has him blocked at the present time. Barring a midseason trade, there doesn’t seem to be much upward mobility for Pohl right now.

Marquez Smith, 1B, Pensacola Blue Wahoos (Cincinnati Reds)

Season: 41 GP, .231/.329/.291, 13 RBI, 16 R, 1-4 SB, 16 BB, 31 K

May: 23 GP, .260/.326/.301, 13 RBI, 8 R, 6 BB, 20 K

I’m still a bit incredulous that Smith still has a role in the Reds’ organization. At 30 years old, he is old for AA, and his lack of power or speed suggests he has gone about as far as he can. In May, he did manage to drive in some runs and improve his batting average, but he strikes out far too often for someone who lacks pop in his bat. Smith will almost certainly be lapped by younger players with better upside as the Reds attempt to rebuild on the fly.