Unfortunately, PTLWs aren’t available for platoon splits (I really wish they were), although you can get pitch selection data from TexasLeaguers.com and break that down for lefties/righties. That gives some help–like it’ll say how often a pitch is swung and missed at, or put into play. It just won’t give the actual run values.

As for why the Padres struggle against lefties, I’d say that it really comes down to the fact that their biggest lineup threat hits lefthanded. Headley’s been awful against lefties too. Unfortunately, Ludwick’s acquisition won’t help that; he has a pronounced reverse platoon split for his career (.238/.316/.454 vs L, .288/.352/.505 vs R).

The Padres don’t have THAT severe of a platoon split this year, though–maybe they hit lefty relievers well or something.

The Padres have a tendency to make any lefty look like Koufax, or at least like Bruce Hurst. Are your pitch selection probabilities overall, or can they be broken down for lefties/righties? There must be some reason the Padres are handcuffed by lefties.