One of the most important trends to follow in Chris Sale's maiden starting pitching voyage this year will be his ability to get right-handers out. That may seem obvious, but putting it into context, only 55 percent of the batters Sale faced as a reliever were righties. As a starter, he can expect about four of every five batters he faces to hit right-handed.
As Eno Sarris at Fangraphs points out, Sale's funky three-quarters release point may make him more prone to significant platoon splits. He's already exhibited those as a reliever -- against lefties, Sale has a 2.10 FIP; against righties, he has a 3.73 FIP.
Going behind those numbers, Sale's walk rate is slightly higher against righties while his strikeout rate is essentially equal. But the reason for Sale's lessened success (and a 3.73 FIP is still successful, for the record) is a much higher home run rate against righties -- of the eight home runs he's allowed in his career, seven have been to righties.
Against lefties, Sale has been exclusively a fastball-slider pitcher. According to Texas Leaguers' pitch fx database, Sale has thrown a grand total of one changeup against a left-handed opponent in his two-year MLB career. That fastball-slider combo should be effective even with facing batters multiple times through the lineup -- it's that good.
Sale's thrown his changeup 13 percent of the time against righties, though, and it's proven to be one of his more successful pitches. Righties swing at it at a higher rate than any of his other pitches (48 percent) while whiffing at it more than any other pitch (18 percent). The swing and whiff rates on his slider and fastball both go down when Sale faces a righty instead of a lefty.
Back to Sarris' point on Sale's release point -- a well-thrown changeup will mitigate those concerns. Sale's slider may be easier to lay off of as righties have a greater exposure to Sale, but the changeup isn't a pitch they should be able to pick up out of Sale's hand.
No matter what Sale does, he'll see some sort of lefty-righty split. He's so good against lefties that it's inevitable. But success with his changeup should narrow the gap.