Napoli's Platoon Split

Mike Napoli homered off Jon Lester Friday afternoon to help the Rangers to a 9-5 win over Boston in the season opener for both teams. In the last three season, Mike, a right-handed batter, owns a large platoon difference, hitting .304 against southpaws and .239 when the pitcher holds the platoon advantage.  Graphically, it looks like this:

Mike Napoli versus left-handed pitchers, 2008-2010.Mike Napoli versus right-handed pitchers, 2008-2010.

What accounts for the difference.  The answer may lie in how pitches tend to move from the various pitchers.  Right-handed batters tend to throw pitches that move away from Napoli:

Mike Napoli, pitch movement from RHP, 2008-2010.Lefties, on the other hand, throw pitches that tend to move toward Mike:

Mike Napoli, pitch movement from LHP, 2008-2010.So what kind of movement does Mike see when he gets a hit versus making an out?

Mike Napoli, pitch movement on hits, 2008-2010.Mike Napoli, pitch movement on outs, 2008-2010.Mike is much more likely to get a hit on a pitch that's moving in than a pitch that's moving away.  Since lefties then to throw toward Mike, it's not surprising he hits them better.  Where does Lester put the ball?

Jon Lester Movement, 2008-2010.It was a perfect matchup for Napoli.