of pitches are thrown by righties. So, if a righty batter has great numbers, he must be able to hit his same handed pitcher. But the same is not necessarily true for lefty batters, who can hide their problems against same handed pitchers because that matchup occurs at most only about 28% of the time and maybe less as the lefty batter may be "rested" against particularly difficult lefty pitchers.
That's a situation that can be exploited in big game situations and there's not much that can be done to help the lefty batter. Of the four possible handed matchups, the worst for a batter is lefty v. lefty.
So, let's look at the two big boppers in question.
Mike Trout v. Bryce Harper:
|5/11/2016||PA||PA v. R||PA % v R||PA % v L||OPS v. R||OPS v. L||OPS||OPS+|
Harper's OPS and OPS+ in 2015 exceeded that of Trout in any of Trout's seasons. But Trout has been an incredibly consistent batter: 2012-2015, BOLD indicates leading his conference (league):
OPS: .963, .988, .939, .991
OPS+: 168, 179, 168, 176
I'd take Trout over Harper. Plus, Harper is an asshole.