Fangraphs looks at Charlie Morton and argues that one reason for his surprising success so far this year has been the fact that he has pitched against an inordinate number of right-handed hitters. Righty hitters haven't been able to do much of anything against Morton this year, whereas lefties have destroyed him.
148 of the 228 batters that Morton has faced this year – a whopping 65% – have been right-handed. The average for all right-handed pitchers in the majors this year is 52%, and that includes relief pitchers who can be selectively used to exploit platoon match-ups. Most starting pitchers have to face predominantly opposite-handed line-ups, and managers especially tend to stack the deck with left-handed bats against RHPs who have demonstrated massive splits.
Morton has dominated the Reds twice this year, for example, and on Wednesday the Reds started a lineup against Morton that featured Joey Votto, Fred Lewis and six righties. It will be interesting to see how Morton adjusts once he starts facing more lefties, as he surely will. He won't be able to depend as heavily on his sinker as he has so far this year; instead, he'll have to work on his changeup, trying to neutralize lefties by mixing up his timing.