I wrote that Cubs Insider post and you actually brought up really fair points that I didn't consider. My main counter to your argument though is that when you evaluate the measurement error using SEM - which imo is a better way to measure variability here - and include his entire career's worth of data, the difference between the cutter and slider classification is so hard to NOT bring up. The probability that it was a random occurrence is like less than .000000001%. I agree that the single start PitchFX analysis can be tedious and most of the time it's not worth reading. But I don't think you can ignore this because of the sharp contrast. Oh, I agree that the classification is significant -- as is the release point difference. I just think that it is hard to tell if he actually "changed" anything about the pitch. It is possible that he and Bosio worked on things and found his stuff played better at that angle. But I think he's slowly been drifting more towards "cutter" status. Velocity going up from start of year; movement down. Interestingly, I feel like it was more of just a nasty cutter in 2015. And by the start of this year, it was basically just a slider. Then I think it reverted back to cutter status by June (albeit a much less nasty one). And then last night was a return to near-2015 levels... which combined with release point change is significant. I was able to significantly associate his in-game release point variability with the amount of slider movement he generated in 2016. So essentially the more inconsistent he was with the pitch, the less movement it generated. That was right around the same time he started to cut his slider usage down a ton. So I think he's been fighting with the "feel" for the pitch for a while. I'm not sure that he consciously wanted to change the way the slider moved. I think it's more he wanted to change something mechanically, which resulted in the difference of pitch classification. Your point of the sinker being different too is a really good one, which is why I think it's more of a total mechanical tweak. The "cutter" is basically the same slider by velo and movement standards, it was just being thrown from a completely different tunnel.