I think at this point that it is widely accepted throughout the sabermetric community that Mike Trout is an overwhelming MVP choice. The more traditional community believes that Miguel Cabrera is an overwhelming MVP because of the Triple Crown that he achieved this year.
Now before you click away because you just saw me mention MVP debate, Mike Trout, and Miguel Cabrera, I ask you to stop. This is because this post is not about who is the MVP, but rather who should finish in second. It is pretty clear that Mike Trout is the bee's knees, and possibly even the cat's pajamas as well.
Somehow Robinson Cano has managed to quietly put together an MVP-type season for the New York Yankees. In 2012 he posted a Fangraphs WAR of 7.9, and a BP WARP of 6.4. He played good defense at a premium position according to both sites (UZR/150 of 9.2, FRAA of 8), which although could be an outlier for him, it is a positive sign that both sites graded him out positively. Plus defenders at premium positions can never be undervalued.
Cabrera on the other hand, posted a Fangraphs WAR of 7.1 and a BP WARP of 6.1. These numbers don't quite delve into the fact that Cabrera was a superior hitter posting a wRC+ of 166 (as opposed to Cano's 148), and a wOBA of .416 (Cano- .392). Although it should be mentioned that Cabrera was 26 points higher in wRC+ over the next third baseman, with Cano being just 13 points better than his runner-up at second base. Cano also finished behind Cabrera in TAv, with the margin being a mere 14 points (.318 to .332).
Obviously small sample-size caveats apply here, but Miguel Cabrera was hands down the worst third baseman in the American League this year according to UZR/150. His -11.2 is 9 points worse than the next worse third baseman, and those two are the only that are negative for the position. It is almost unfair to even call Cabrera a third baseman, as he clearly lacks the ability to play it failing both the eye test and the stat test. Baseball Prospectus is a bit kinder to him only grading him as 2.3 runs worse than average in the field, but the general point here is that we can all agree defense is not his strong suit.
To sum up my argument: I believe that Robinson Cano has been more valuable this season because he was able to post an offensive performance near Cabrera's level while playing much better defense at a premium position.