If there is one thing the Royals had plenty of this year, it was good, solid (sometimes great) production from a plethora of rookies who made their debuts this past season. The largest area of note was the bullpen, where the likes of Louis Coleman, Aaron Crow, and Greg Holland each saw a measure of success.
On the position player side of things, Eric Hosmer performed well as a rookie first baseman. Mike Moustakas ended the season with a huge surge (from Aug. 15th to the end of the season (156 PAs), Mike hit .365/.397/.541 with 4 HR and 19 RBI in 38 games). Johnny Giavotella showed some flashes (he had a good first week and a good last ten days, but in between was pretty bad). Sal Perez mashed for 39 games (who misses maintaining his rookie eligibility by 19 at-bats, I believe).
Though, as Highlander has taught us, there can be only one, and really this comes down to two players: Holland and Hosmer.
Greg Holland had phenomenal success out of the bullpen this year, throwing sixty innings with 74 strikeouts to only 19 walks. He managed to score 2.0 fWAR with an ERA/FIP/xFIP of 1.81/2.21/2.67. He also gave up only 37 hits.
Eric Hosmer ended the season with a .293/.334/.465 line with 19 HR, 78 RBI, and 66 runs in 128 games (he also stole 11 bases in 16 attempts, so, yeah). He scored only 1.6 fWAR, owed in large part to a steep positional adjustment and the fact that his defensive metrics do not grade him out as the "exceptional defensive first baseman" that you may have read about (small sample size), nor was he horrendous in the field, getting -7.0 FLD runs according to FanGraphs (for an interesting contrast, Billy Butler spent 272 games at first between 2009 and 2010, and accumulated only -4.7 FLD runs).
This weekend, I'll do a write-up on Part 6 of this series, the Royals' 2011 MVP Alex Gordon (I didn't think a poll was necessary to figure out that one).