Pretend, for a moment, that the 2012 season has not gone as it has. Bryce Harper is never called up to the Nationals, or at least not until rosters expand in September, because Jayson Werth remains healthy all season.
This second bit will take nearly all of your imagination, but construct a world in your mind where Vernon Wells is both healthy and useful, and Mike Trout sits in Triple-A, preparing himself for the 2013 role he is sure to have once Torii Hunter departs as a free agent.
Why bother with this thought exercise? It's because Trout and Harper are the most-discussed rookies in a freshman crop that deserves to have that attention spread out more. It's not that Trout and Harper aren't excellent rookies, especially when you account for their tender ages, but that so many other rookies are having their own impressive debut campaigns overshadowed because of them. Especially in the American League, where Trout is likely to win both Rookie of the Year and Most Valuable Player honors, something that's occurred just twice before: in 1975, when Fred Lynn pulled it off (while teammate Jim Rice finished third and second in the MVP and Rookie of the Year vote, respectively) and in 2001, when Japanese import Ichiro Suzuki became Ichiro! in his first year in the states.
This is basic, but according to Baseball Prospectus' wins above replacement player (WARP), there are eight rookies besides Trout and Harper who have accumulated at least two wins in 2012. There were nine such players total in 2011, just four in 2010, and 10 in 2009. None of these seasons featured someone as valuable as Trout, though, and except for Buster Posey and Jason Heyward, none even as valuable as Harper. Even sans Trout and Harper, there's an argument to be made this is the most productive rookie class in recent memory.
Mike Fiers leads the way for pitchers with three WARP, thanks to 117 innings over 20 starts and a 123 ERA+. Fiers might be an unconventional rookie as a 27-year-old, but the rules still apply to him, and his performance has helped the Brewers move from sellers at the deadline to contending within the season's last two weeks. Then there is Yu Darvish, who, despite maybe not reaching the levels of hype attached to him during the offseason, still owns a 116 ERA+ and is second among all rookie hurlers in WARP. He has made 28 turns in the rotation, threw 184 innings, made the All-Star team, and he's struck out over 10 batters per nine on the year. Not bad for his first go of things in MLB.
There are more conventional rookies around as well. The Rays' Matt Moore has taken his lumps as an AL East rookie pitcher, but it's hard to argue with a punch-out per inning and a league-average ERA in the 23-year-old's first full season. Lance Lynn made a name for himself down the stretch and in the playoffs last year, but he still qualifies as a rookie in 2012: The Cardinals' pitcher has made 27 starts, earned an All-Star berth, and has whiffed just under a batter per inning with a 2.7 K/BB in his 163 frames. The Diamondbacks have leaned heavily on Wade Miley, who has improved as the year has gone on, and now sports nearly four times as many strikeouts as free passes in his 177 innings. Kelvin Herrera is the last pitcher over two wins, despite being a reliever. It's easy to understand how he's achieved that, though, if you look at his numbers: The right-hander has thrown 80 innings in 71 games, with a 3.9 strikeout-to-walk ratio and 176 ERA+ to go along with stranding 73 percent of inherited runners.
Offensively, there's Yoenis Cespedes, the Cuban import signed by the A's this year. He's played in left, center, and at designated hitter, all the while sporting a .294/.354/.488 line in spite of O.co Coliseum's pitcher-friendly dimensions. Cespedes trails just Trout and Harper in rookie WARP, not just for position players, but all rookies -- in any other year, we'd be salivating over the 26-year-old. Milwaukee's Norichika Aoki sports not only an excellent name, but a 113 OPS+, 2.3 WARP, and 28 steals in 35 chances in his 137 games.
That's just the player who have cleared our arbitrary two-win threshold. Anthony Rizzo was called up in late June, and has hit .286/.348/.480 with 14 homers since. Yonder Alonso began the year slowly, but owns a 124 OPS+ since the All-Star break. Teammate Yasmani Grandal has appeared in just 48 games between a late call and his role as catcher, but is hitting .280/.386/.465 despite the rigors of backstop life and Petco Park's environment. Will Middlebrooks picked up 1.5 WARP and was on pace for over 30 homers in a full season before breaking his wrist on a hit by pitch. Matt Carpenter has hit .297/.364/.486 for the Cardinals while playing at every corner position on the diamond, and even at the keystone when needed. Todd Frazier can't seem to hit his way into a full-time gig in the Reds' lineup, but it hasn't dismayed him, says his .510 slugging and 121 OPS+.
Pitchers have the same situation, with every other pitcher in the A's rotation a rookie performing well, Wei-Yin Chen one of the only stable pieces in the Orioles' rotation, and non-prospects like Jose Quintana and Miguel Gonzalez helping to push their respective clubs to surprising playoff berths.
There's no end to productive rookies this year, even in an imagined world without Trout and Harper. What pushes this season over the edge, though, is that we do have Mike Trout and Bryce Harper around. And if this is what they are doing as rookies, then we're all in for quite a treat in the future. Especially with a supporting cast as strong as this one.