2008
Winner - Geovany Soto
Why he won - .285/.364/.504 as a catcher on the best team in the league
What he's done since - While it has only been one season since, Soto saw a huge regression. This season he's batting .219/.327/.383 in 87 games. He recently lost games to Koyie Hill, he of the 53 career OPS+. In the minors though, he had a poor OPS until 2007. Perhaps he is just regressing to his true level.
Other players to receive votes - Joey Votto, Jair Jurrjens
2007
Winner - Ryan Braun
Why - .324/.370/.634, 34 HR, 15 SB
Since - Braun was the best player in what is likely the decades best rookie class. Troy Tulowitzki gave Braun a run for the award and likely had more VALUE thanks to his far superior defense. Braun was a force as at the plate though. Since 2007, Braun has moved to Left field. He's still no defensive wizard but he offsets his defensive inadequacies with a 140 OPS+
Others - Tulowitzki, Hunter Pence, James Loney, Yunel Escobar
2006
Winner - Hanley Ramirez
Why - .282/.353/.480 with 51 SB's
Since - This was the year of the Marlins as they had 6 players receiving votes. Ramirez has become a star since then, punching up a 141 OPS+ with 169 steals to boot. His defense is erratic at SS but he makes up for it at the plate. He finally was put in a spot in the batting order where he belongs, dropping form the leadoff to the third spot. He's responded with a career high slash line of .358/.422/.575.
Others - Ryan Zimmerman, Dan Uggla, Prince Fielder
2005
Winner - Ryan Howard
Why - .288/.356/.567 with 22 HR's
Since - Howard won an MVP the next year (even though Pujols' numbers were better). His defense has been bad and his batting average has fallen and his strikeout numbers have been absurd. He's become a Three True Outcomes player with a solid OPS+ (career 141).
Others - Willy Taveras, Jeff Francoeur, Garrett Atkins (fairly weak class)
2004
Winner - Jason Bay
Why - .282/.358/.550 with 26 HR's
Since - Bay is the first player to move to a new team. Now on the Red Sox, Bay has been a key component this season. In another weak class, Bay put up the best numbers. Bay's career numbers are pretty solid, with a career 131 OPS+. His defense isn't great but he has been a solid, above average player in his career.
Others - Matt Holliday, Aaron Miles (as stated, weak class), Khalil Greene
2003
Winner - Dontrelle Willis
Why - 14-6 3.30 ERA 142 SO's
Since - Willis has been moved to the Detroit Tigers and become a sad story of inconsistency. He has no control and has been through all the minors again. It doesn't look good for his career. Brandon Webb was probably a better candidate for ROY, but Willis had all that charisma.
Others - Webb, Miguel Cabrera, Jose Reyes
2002
Winner - Jason Jennings
Why - 16-8 4.52 ERA 127 SO's
Since - Jennings numbers his rookie year were nothing special, but he had the advantage of winning a bunch of games. Jennings has moved on to the Texas teams the last couple years, pitching one season for Houston and the last two for the Rangers. He's been converted to a reliever this year after only posting one season with above average numbers after his rookie year (2006).
Others - Austin Kearns, Josh Fogg, Mark Prior (yet another down year for rookies)
2001
Winner - Albert Pujols
Why - .329/.403/.610 with 37 HR's
Since - What ever came of that Pujols fellow? He's only become the best hitter in baseball and a gold glove defender. He hits for power (364 HR's), average (.334 career batting average), and everything in between (172 career OPS+). He has 2 MVP awards and will likely win a third this season. He's the best player in baseball.
Others - Roy Oswalt, Jimmy Rollins, Adam Dunn
2000
Winner - Rafael Furcal
Why - .295/.394/.382 with 40 SB's
Since - Furcal has never been an elite hitter. A lot of his value has been tied into his speed but that has been in decline the last few seasons. He has a .349 career OBP, which is a little low for a "leadoff" guy. He's always had a cannon for an arm but has never won a Gold Glove and likely won't. It's safe to say he's in the decline phase of his career as a "31" year old.
Others - Rick Ankiel, Pat Burrell, Lance Berkman
As we can see from this little study, sometimes the voters knock it out of the park (Pujols). Sometimes they miss (Jennings). A lot of it depends on the class. This season has some guys that should be solid players (Colby Rasmus, Chris Coghlan, Andrew McCutcheon) to go with some good pitching performances (J.A. Happ, Tommy Hanson). Only time will tell whether the voters hit it out or not.