That's often how it is done, but doesn't have to be. 1) What's important for platooning isn't the batter's handedness, but how he does against pitchers of one hand versus the other*. Garver seems to have a normal platoon split in his time in the majors, doing a little better against lefty pitchers (but hardly futile against righties). But Jeffers showed an opposite-platoon split in his short time in the majors last year, and his 2019 and 2018 in the minors were likewise. For practical purposes, Jeffers's results looks like he hits as though he were a lefty. 2) Platooning at catcher isn't like at other positions. You might platoon in left field because you don't have a satisfactory guy to play there everyday, which would be one's normal preference - so you cobble together the equivalent, from two players with complementary abilities - but you would not platoon two stud hitters in LF just for the sake of lefty/righty splits, instead you'd find some solution that gets them both in the lineup, or trade one of them. But at catcher, it's a given that no one is enough of an ironman to start 162 games. The ideal for catcher is to have two guys who both hit so well that you're happy to have either one start on a given day, and can decide perhaps on a given opposing matchup on the mound that day if both are rested. It is possible we have that situation right now, if Garver bounces back, and Jeffers proves to be the real deal. * A few pitchers likewise have reverse platoon splits, which complicates the record-keeping a bit. I imagine advanced analytics teams have this detail sorted out by now.