Switch hitter Matt Wieters of the Baltimore Orioles improved his batting average and slugging percentage by about 20 points this season, meaning he's hitting on average more singles. His improvement came almost entirely against left-handed pitchers. In 2010, he hit .210 against southpaws and .263 against right-handed pitchers. This season, he's up to .303 against left-handers, with he dropped to .247 against righties.
In 2010, he got very little production against LHP in the middle of the plate.
He was fine inside and outside, but up and down in the middle was a cold wasteland. He swung a lot a inside pitches against lefties that year:
He swung at 53.6% of pitches inside last season. This year, that's down to 37.6%. The difference is obvious on the more recent heat map:
Matt now swings in the strike zone where he managed little production in 2010. The results?
He's swinging at pitches that are easier to hit, and driving the balls for hits. Now he just needs to figure out something similar against righties.