Since we are around the mid-season point, I figured now would be a good time to talk Rookie of the Year. While there haven't been huge performances to date, a few rookies do stand out. I'm only going to mention people with over 100 AB.
Colby Rasmus - Rasmus has more AB than any other rookie and has a triple slash line of 270/313/455. The walks really aren't there yet, but the power has been nice. According to UZR, Rasmus has been great this season being +10 in the OF.
Andrew McCutchen - Just over 100 AB at this point, but he has impressed. Only one homerun to date, but 5 triples. Obviously, we'll need a larger sample size.
Chris Coghlan - He has played 2B in the minors, but is now in the OF blocked by Uggla. His 262/360/360 line isn't great, but he has shown some pop in the minors. With the Marlins in the chase, he'll need to step it up a little.
Tommy Hanson - He has really battled this year getting to 4-0, his SO are down in the MLB and his walks are way up, but his ERA is a shiny 2.48. His LOB% is an insanely high 87.6% so his ERA should rise. If he can keep the hits down, as he has and stop walking batters he could put together a nice year.
Kenshin Kawakami - Another Braves pitcher. He was signed out of Japan and is 34. 4-6 with a 4.25 ERA, he has missed a good amount of bats, but the walks are a little high. His numbers look solid, but one has to wonder if he'll start to let up a few more HR.
Jordan Zimmermann - Zimmermann has great SO numbers, and not an awful amount of walks (8.92 K/9, 2.50 BB/9).. His ERA is high for a Rookie of the Year candidate (4.52) but that has to be a product of the Nationals league worst defense to some degree. His FIP stands more than a full run lower than his ERA at 3.38. With improved defense behind him, and some better luck, Zimmermann could pull away from this pack. That could be a nice story for the Nats (whom rarely have nice stories). He'll have to win more games, because one has to assume that Hanson will improve.
Nolan Reimold - One of two AL players with over 100 AB (his teammate Weiters is at 85 with an OPS of 685) he has crushed the ball thus far. His OPS is 883, the highest of any rookie by a large margin. His 9 HR also lead all rookies, and he has a nice K/BB ratio 24/17. His wOBA is 383. However, his defense hasn't been great UZR has him at -11 thus far in the OF.
Elvis Andrus - One can't say the same about Andrus's defense. Anchoring SS during a revival of the Ranger's defense. UZR has him at +5.3. While he hasn't shown much with the bat, he has exceeded my expectations by a large margin. 269/330/380 is his current line, but one can't over look his 15 SB with just 1 CS.
Ricky Romero - He has been pretty filthy lately. His season stats are looing great at this point, 2.85 ERA with 61 SO in 72.2 IP. However, like Hanson his strand rate is awfully high at 86.9% and his FIP shows some regression in his ERA. The 6-3 record will help him with voters though, especially if he can duplicate that record in the 2nd half.
Brad Bergesen - Kind of a dark horse here, but his ERA is a nice 3.53. I don't this he has the stuff though moving forward. His SO are extremely low, and his BABAIP is quite low as well.
Rick Porcello - The 20 year old top prospect has throwing 83 innings already this season with a 3.80 ERA. His GB rate has been great, but he really needs to miss more bats (4.77 K/9). He has been hurt by the long ball, and those numbers could regress. Though, when a pitcher is only has a 20% FB rate, I guess he'll have a few more go out. His 8 wins put him in great position though.
Andrew Bailey - Bailey has sliced his way through the AL this season dominating batters in the late innings. His SO rate is phenominal (10.84) and while his walks are high, they aren't awful (3.61 BB/9) especially when he isn't allowing many hits. Baily does have some regression coming to his stats though. His BABIP (254) LOB% (84.5%) and HR rate 5.8% per FB all could bring his ERA (2.09) down.
(AL Notables - Matt Weiters and Gordon Beckham)
I'm going to take Zimmermann and Porcello with the runners up being Rasmus (followed by Hanson) and Gordon Beckham (followed by Nolan Reimold). I think the addition of Nyger Morgan will help Nationals pitchers immensly. Porcello's also a great story with pedigree. Pitching this well at his age 20 season is going to be tough to beat. He'll need those other guys to regress some though.
Sorry if you think I missed someone.