An all-star team comprised of prospects, based on their performance in the minors during the month of May.



The runs above average estimates are calculated by Baseball America. For batters, weighted on-base average (wOBA) is used to calculate RAA. For pitchers, runs allowed per nine innings (R/9) is used.



PA stands for plate appearances. Also available: the April prospect all-star team.



C Zack Collins | White Sox

Double-A Birmingham (Southern) | 13.8 RAA



The ultra-disciplined catcher led all minor league batters with 33 walks in May, pushing him toward the top of the Southern League in on-base percentage. Collins hit .322/.508/.540 with five home runs in 122 PA as the lefthanded-hitting complement to Seby Zavala and Birmingham's powerful catching tandem.

1B Daniel Vogelbach | Mariners

Triple-A Tacoma (Pacific Coast League) | 11.2 RAA



The Mariners were on a roll in May, and so was Vogelbach at Tacoma after being demoted there in April. He used his revamped hitting approach to slash .329/.465/.684 with seven home runs in 101 PA, all while collecting more walks (20) than strikeouts (12).

2B Keston Hiura | Brewers

High Class A Carolina (Carolina) | 14.6 RAA



One of the most accomplished college hitters of the century, Hiura hit just .238 in the Carolina League in April before busting out in May. He hit .377/.437/.664 with six home runs and 13 doubles in 135 PA, which earned him a promotion to Double-A Biloxi. Equally encouraging: Hiura began playing second base in May (15 games) after playing DH exclusively in April as he dealt with a sore elbow.

3B Vladimir Guerrero Jr. | Blue Jays

Double-A New Hampshire (Eastern) | 20.1 RAA



Among minor league batters with at least 100 PA in May, Guerrero led the field with a .438 average while tying for the lead with nine home runs. He accomplished that as a 19-year-old in Double-A, which helped propel him to No. 1 on the Top 100 Prospects ranking updated for June.

SS Fernando Tatis Jr. | Padres

Double-A San Antonio (Texas) | 11.9 RAA



Blue Jays shortstop Kevin Smith continued to rake at low Class A Lansing in May, but the nod here went to the 19-year-old in Double-A. Tatis hit just .177 in the Texas League in April but surged to a .336/.414/.639 line in May with seven home runs and 12 doubles in 140 PA.

OF Eloy Jimenez | White Sox

Double-A Birmingham (Southern) | 12.7 RAA



Jimenez spotted the rest of the Southern League a couple weeks as he recovered from a pectoral strain in April. But after hitting .374/.419/.664 in May with six home runs in 117 PA, he vaulted the SL boards and now ranks among the leaders in homers, RBIs and slugging.

OF Alex Kirilloff | Twins

Low Class A Cedar Rapids (Midwest) | 11.7 RAA



After missing the entire 2017 season while recovering from Tommy John surgery, Kirilloff has showed no rust in the Midwest League while making his full-season debut. He hit .360/.423/.640 with five home runs in 130 PA in May.

OF Juan Soto | Nationals

Double-A Harrisburg (Eastern) | 12.3 RAA



Soto compiled just 72 minor league PA in May—but that can't be held against the 19-year-old when the reason for the brevity was his callup to the big leagues. He spent nine games in May at high Class A Potomac, another eight at Double-A Harrisburg and the final 12 in Washington. On the minor league side, Soto hit .397/.472/.841 and led all batters with a .444 isolated slugging percentage while also compiling nearly as many walks (nine) as strikeouts (10).

RHP Shane Bieber | Indians

Triple-A Columbus (International) | 12.5 RAA



Bieber continued to paint the strike zone with command of four pitches during his first test at Triple-A in May. He recorded a 1.05 ERA in five starts while striking out 31, walking two and allowing 17 hits in 34.1 innings. That earned Bieber a major league start for Cleveland on May 31.

RHP Jonathan Hernandez | Rangers

High Class A Down East (Carolina) | 10.8 RAA



Hernandez complemented his huge fastball with improved mechanics and secondary pitches this year. The results in May were noteworthy: He recorded a 1.69 ERA in five starts while striking out 45, walking nine and allowing 16 hits in 32 innings.

LHP Brendan McKay | Rays

High Class A Charlotte (Florida State) | 10.6 RAA



The 2017 College Player of the Year, McKay had no trouble with Class A competition in May, either at low Class A Bowling Green or Charlotte. He walked just two batters and allowed 10 hits against 35 strikeouts in 27.2 innings. That helped him post a 1.30 ERA in five appearances.



LHP Cionel Perez | Astros

Double-A Corpus Christi (Texas) | 11.0 RAA



Perez's strikeout rate took a giant leap forward in May, when he fanned 38 in 26.2 innings while allowing eight walks and 16 hits. The Cuban lefthander went 3-0 with a 1.35 ERA in five starts.



LHP Will Stewart | Phillies

Low Class A Lakewood (South Atlantic) | 13.7 RAA



The 20th-round high school pick out Alabama in 2015, Stewart has grown into a bit more velocity and a whole lot of maturity this season. He pitches in the low 90s and backs it with improving secondary weapons he used on his way to a 0.74 ERA in six May starts, when he struck out 34, walked seven and allowed 23 hits in 36.2 innings.