Where will Mike Trout end up on the list of baseball greats?Well, considering his current statistical achievements (2 seasons of 10+ Wins Above Replacement in his first two years in the majors, 4th youngest player to hit for the cycle, and has twice been snubbed for the AL MVP (in favor of Miguel Cabrera's Triple Crown and...There's no reason he shouldn't have won last year), leading the MLB in Runs Scored in 2012 and '13, 1st in OPS+ in '12, 2nd in '13, 1st in '14 so far... I could go on), Mike Trout projects as one of the best baseball players in history. He is currently leading the MLB with 5.1 WAR as of this writing, and a serious contender to actually win the AL MVP (especially since Miggy is having a slightly down year and Masahiro Tanaka is now injured).
His similarity score (career arc modeling tool provided by Fangraphs) most closely resembles (in this order) Frank Robinson*, Mickey Mantle*, Orlando Cepada*, Al Kaline*, Jimmie Foxx*, Ted Williams*, Hank Aaron*, and Ken Griffey. Everyone with an asterisk is in the Hall of Fame already, and Griffey will get there.
There are problems, however, that might keep Trout from matching these legends. Injury is an ever-present threat, and Trout has a massive frame. He plays all-out all the time (I'm looking at you, Bryce Harper!) and this could lead him to have a bit shorter career or an eventual move to first base or right field as he ages and loses a step. He has had trouble covering the top of the strike zone this year, and pitchers are beginning to exploit this hole in his swing. In short, for as great as he is, Mike Trout may have peaked already. I really like the Ken Griffey comparison--he was extremely dominant early in his career, and played until 40, but he only had one year of 3+ WAR after his 29th birthday after posting 12 consecutive seasons of 3+ WAR prior to it.
I think Trout will have a great career, but the other athletes get paid, too. Pitchers will find holes in his swing and his body will eventually fail him, but not before he makes his mark among the greats. If he can keep putting up 10 WAR seasons into his 30's, he will be remembered as the best player of his generation.