The top four prospects in baseball entering the season—Bryce Harper, Matt Moore, Mike Trout and Yu Darvish—all have spent the majority of 2012 in the big leagues. All but Moore appear on the midseason all-rookie team, and his exclusion might be the most unexpected given the lefty’s dominance for the Rays last September and October.
Despite the extreme youth of Harper and Trout—their combined age of 39 is younger than 12 active big leaguers—both the batting and pitching rookies skew older at an average age of 24 years old. The Athletics, Rangers and Reds each placed multiple rookies on the midseason team, including Oakland No. 1 prospect Jarrod Parker, Texas No. 1 Darvish and Cincinnati No. 5 Zack Cozart.
Statistics here capture a snapshot of each player's performance at the end of the day July 8, the final Sunday prior to the all-star break. Rookies are organized into four groups so that performances can be compared more directly. Players are divided into starting pitchers, relief pitchers, up-the-middle defenders and corner players, because no one ought to expect a middle infielder's raw offensive production to look like a corner outfielder's.
An asterisk (*) denotes a lefthanded batter or thrower and a pound sign (#) signifies a switch-hitter.
Catcher, Second Base, Shortstop & Center Field
• The Mariners' Jesus Montero and the Reds' Devin Mesoraco entered the season with more rookie fanfare (and attendant No. 1 prospect status in their organizations), but the Rockies' Wilin Rosario wrested the starting job away from veteran Ramon Hernandez in May and hasn't looked back. Rosario belted 14 homers in the first half to lead all rookies, so despite an acute on-base deficiency (eight walks, 53 walks and a .279 OBP) he gets the nod at catcher—at least for now.
• Talent ebbs and flows at each position in the big leagues, and nowhere is that more apparent than at the keystone. Last season, Dustin Ackley, Jemile Weeks, Danny Espinosa and Jason Kipnis all vied for top honors among rookie second basemen. The challengers this season pale in comparison. The Phillies' Freddy Galvis has the playing-time advantage, having opened the year as an injury replacement for Chase Utley, but the 22-year-old batted just .226/.254/.363 through 58 games and then landed on the restricted list following a drug suspension. That opened the door for another injury fill-in, the Dodgers' Elian Herrera, who briefly replaced Mark Ellis at second base but actually has started more games at third and in the outfield. Signed out of the Dominican in 2003, Herrera is the most senior member of the rookie team at 27.
• The Reds turned over shortstop to Zack Cozart on Opening Day, and while he scuffled as a leadoff hitter (.269 OBP in 287 plate appearances), he provided steady defensive work and an adjusted-OPS (86 OPS+) not so far removed from NL veterans such as Jose Reyes (91 OPS+), Jimmy Rollins (92) and Rafael Furcal (93). Cozart's prime challenger in the second half figures to be the Braves' Andrelton Simmons, who batted .296/.336/.452 in 33 games and accumulated incredible defensive value following a callup from Double-A—but then he broke his right pinky in a headfirst slide in the final game of the first half.
• The Angels' Mike Trout ranked as the top prospect in every minor league in which he played, topping it off with Minor League Player of the Year honors last fall. That might be the tip of the iceberg for the 20-year-old center fielder, who led the AL in average (.341) and stolen bases (26) at the break, making him the leading contender for the league's Rookie of the Year award and perhaps the MVP. Oh yeah, and he went 1-for-1 with a walk and a stolen base in the All-Star Game.
First Base, Third Base, Left Field, Right Field & Designated Hitter
• Typically an organization that loses access to Albert Pujols and Lance Berkman one season after winning the World Series would see its first-base production plummet. But that hasn't been the case for the Cardinals, who have received an .898 OPS at first base, thanks to Allen Craig and a pair of rookie Matts, both drafted after the 10th round in 2009. Matt Adams (23rd round) and, particularly, Matt Carpenter (13th) have softened the blow of Pujols' defection and injuries to Berkman and Craig. Carpenter shifted back to a third base/corner-outfield rotation following Craig's return, but he doesn't presently have much competition at first base for the midseason rookie team. The Padres’ Yonder Alonso has about twice the playing time but hasn't done as much with it, batting .263/.344/.362 in 293 at-bats, which even when neutralized for Petco Park is merely league average.
• Red Sox top prospect Will Middlebrooks hit nine homers in 24 games for Triple-A Pawtucket prior to his May 2 callup, then proceeded to hit 10 more in the big leagues and succeed Kevin Youkilis as Red Sox third baseman. He's already eclipsed his career high for homers, which he set last year with 18 for Double-A Portland, so the power definitely profiles on a corner.
• Though he's been beset by injuries to his hand, hamstring and thumb, Yoenis Cespedes has flashed the explosive tools—including monster power—that the Athletics coveted when they signed the 26-year-old Cuban to a four-year, $36 million pact.
• The No. 1 overall prospect in baseball this spring, Bryce Harper has matured into the top hitter (or close enough to it to make no difference) for the Nationals, the NL’s top club, at the tender age of 19. He took over center field on a full-time basis May 30, and from that date batted .281/.342/.432 with 13 extra-base hits in 34 games.
• The Reds finally entrusted 26-year-old Todd Frazier with regular play at third base (following an injury to Scott Rolen) and he's rewarded them with a .906 OPS that trails only Mike Trout among rookies.
• The Orioles acquired their two most effective first-half starters in unheralded offseason transactions, acquiring Jason Hammel in the Jeremy Guthrie trade with the Rockies and signing Japanese majors veteran Wei-Yin Chen as an international free agent. (They haven't yet seen a return on fellow Japanese leagues import Tsuyoshi Wada, who had Tommy John surgery in May.) A Taiwanese national, Chen spent the last four years in the Chunichi rotation but a leg injury in 2011 may have scared other U.S. teams away.
• Rangers $60 million man Yu Darvish has shined at times—he notched five double-digit strikeout games in 16 starts and ranks second in the AL in strikeout rate—but hasn’t yet scaled heights he did in Japan. He closed out the first half with four strong starts in a row, going 3-1, 3.30 with 40 strikeouts and nine walks in 30 innings. Of course, it didn't hurt that three of his opponents were the Astros, Padres and Athletics.
• A nondrafted free agent out of college and a veteran of the Rule 5 draft, the Twins' Scott Diamond improved his big league fortune this season by dramatically improving his control, shaving two full walks per game off his rate. He leads all rookie starters in walk rate (1.4 walks per nine innings) and in groundball percentage (59 percent of balls in play), which helps cover for one of the lowest strikeout rates.
• Wade Miley seamlessly replaced Daniel Hudson in the Diamondbacks rotation, and the four-pitch lefty seems to have held onto his 2011 gains. He struck out 47 and walked 12 in 40 innings down the stretch for Triple-A Reno last season, earning a callup to Arizona in August. Miley's fastball (91 mph) and slider (81.5) have been thrown with greater velocity this season than last, according to Pitch f/x, and he made the NL all-star team.
• The lynchpin of the Trevor Cahill deal with the Diamondbacks, Jarrod Parker already rates as one of Athletics' top starters at the ripe old age of 23. His underlying peripherals do not suggest he'll carry a sub-3.00 ERA through 180 innings, and neither do his road results (3.74 ERA, 1.37 WHIP in six turns), but at least this time Oakland acquired a top-flight Arizona pitching prospect after he had Tommy John surgery, which was not the case with Brett Anderson.
Not eligible for AL or NL rookie of the year awards because they had too much service time in past season(s): Padres RHP Anthony Bass, Athletics LHP Travis Blackley, Red Sox LHP Felix Doubront and Cardinals RHP Lance Lynn.
• From third round of the 2010 draft to the closer's hot seat in Chicago in less than two years, White Sox righty Addison Reed throws as hard (94.7 mph, according to Pitch f/x) as any rookie reliever this side of the Royals' Kelvin Herrera (97.1 mph). He continues in the tradition of power-armed South Side rookie relievers such as Chris Sale last year and Sergio Santos in 2010. The only rookie reliever to allow a higher flyball percentage than Reed (48.8 percent of balls in play) is White Sox teammate Hector Santiago, which would seem to be an imperfect union between player and home ballpark.
Don't judge Reed too harshly by his ERA—if not for a one-out appearance in which he allowed six runs to the Royals on May 13, his ERA would be 2.35.
• Another piece of the Athletics' haul for Trevor Cahill, righty Ryan Cook began the year in a set-up role before supplanting Brian Fuentes and Grant Balfour as Oakland closer in mid-June. He made 22 straight scoreless appearances to begin the season, and then notched 12 strikeouts while allowing 12 baserunners in 11 1/3 innings after taking over the ninth inning. One of five rookies to earn all-star status this season, Cook pitched a perfect seventh inning for the American League, striking out Bryce Harper and David Wright looking.
• Lefthander Robbie Ross finished last season by making six starts with Double-Frisco, and this spring he admitted to feeling shocked when he made the Rangers' Opening Day roster. He's more than carried his weight as a rookie, ranking third among AL relievers in opponent average (.204) and unintentional walk rate (1.9 per nine innings), while also inducing groundballs on 65 percent of all balls in play he allows, a rate that leads all rookies.
Not eligible for AL or NL rookie of the year awards because they had too much service time in past season(s): Dodgers RHP Josh Lindblom, Rays LHP Jake McGee, Orioles RHP Pedro Strop, Orioles LHP Troy Patton, Tigers RHP Brayan Villarreal and Mariners RHP Tom Wilhelmsen.