The Phillies need outfielders. John Mayberry, Jr. is an outfielder, or at least half of one.
.245/.301/.395, 14 home runs, 479 plate appearances.
7.1% walk rate, 23.2% strikeout rate
John Mayberry, Jr. is a useful baseball player. He hits/throws right-handed and he plays pretty decent outfield defense. He has limitations, particularly in that he does not hit right-handed pitching very well at all. In short, he is a platoon player, playing on the short side of the platoon. Since he is effective against lefties, that's who he should play against. For the National League last year, there were about 98,000 plate appearances. About 28,000 of those were against left-handed pitching, or roughly 29%.
Mayberry was a decent fielder and baserunner in 2011, but these numbers tailed off last year, and he cost the team runs in both categories, if you believe in the statistics aggregated by Fangraphs. On average, he is probably a low-end centerfield defender and a better-than-average defender in left.
There is little reason to expect that he will suddenly transform into something other than what he has shown so far. While he has only 303 Major League Baseball games under his belt, he is 29 this year, and will turn 30 in December. This is a flower that is no longer blooming, barring some Kafkaesque transformation into the Jose Bautista of cockroaches.
His on-base skills are marginal to poor, even against lefties. In his 180 plate appearances against lefties, his on-base percentage was only .317, despite the outcomes generating a wOBA of .345 driven by a quite ordinary .289 BABIP. He was good for a wRC+ of 116 against lefties. The story for Mayberry is basically average to poor on-base skills coupled with decent power against lefties.
Against right-handed pitching, he was awful in 2012, with a wRC+ of 70. In a pretty good 2011 campaign, it was 116 against right-handers, but 158 against lefties. The issue is one of degree, perhaps, but his platoon split looks real, with a lifetime vs. lefty wRC+ of 133 and vs. righty of 86. The big difference is that he hits tons of grounders against right-handers: 52% versus 40% for lefties. In addition to hitting more fly balls against lefties, his fly balls are more often home runs against lefties, too.
For a half-million bucks as a pre-arbitration player, he's useful, but he is of limited utility unless he can stop grounding out against right-handed pitching or until his manager uses him as a straight platoon part. An OPS of .811 is far better than one of .626. It isn't Mayberry's fault that he hits same-handed pitching poorly, but it is his manager's fault that he is improperly used. There is no real reason why he should get 299 plate appearances against right-handed pitching again this year, but he probably will.
.257/.313/.440, 11 home runs, 306 plate appearances
.248/.306/.420, 15 home runs, 431 plate appearances
.248/.303/.410, 15 home runs, 478 plate appearances