According to bref defensive WAR measure, Mike Trout is a -0.8 WAR fielder (Cabrera is -0.5). He hasn't appeared to be as good this year as last year, but I wouldn't have thought he was actually negative. It makes you wonder about his weight gain if we take this to be an accurate assessment of his fielding. If it is not an accurate measurement, then what should we think about last season? Is there some other reason why his fielding has been bad this year?