Since the start of the 2009 season, Matt Cain of the Giants recorded better results against left-handed batters than right-handed batters despite Matt throwing from the right side. Left-handers hit .224/.282/.360 against Matt, while righties managed a .231/.295/.380 slash line. How does Matt manage to keep lefties so off balance?
The first thing to notice is that Cain works lefties away:
Left-handed power hitters like the ball low and inside, so this should be a good strategy. Cain adds to it, however, with the movement of his pitches. While he works outside, his four pitches move inside:
His fastball in orange, changeup and slider in green (slider closer to the batter) and curve ball in blue all move toward a left-handed batter most of the time. So Cain can start these pitches outside the strike zone, and have them break over the plate. So left-handed batters often see ball, but then end up with the ball over the plate. His fastball and curve ball result in over one third of the time, while his change and slider get chased out of the zone over 40% of the time. Lefties get fooled.
Finally, here's what happens when lefties put the ball in play:
They hit him well down and in, the main area Cain avoids with his pitches. He uses movement to fool left-handed batters in and out of the zone, and throws where these batters don't hit well. The result makes Cain as good if not better when the batter owns the platoon advantage.