Is there any systematic evidence that long term, certain pitchers generate worse contact than others, other than in terms of the crude categofies of GB, LD and FB? In other words, is there any systematic evidence that xwOBA ads anything to FIP (or SIERA which I think already takes into account GB%) other than short-term randomness? I'm open to the possibility, but I haven't seen it. Certainly certain hitters generate better launch angles and exit velocities on FB/LD, but that doesn't necessarily mean that certain pitchers do. That being said, this is an interesting analysis.