I think there was a real tangible difference between who he was against the blue jays and who he was against the mets and that isn't just quality of competition.
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That was his last start against the blue jays (an abject disaster). You can see his four seamer was all over the place and his slider was mostly non competitive. those are his two most frequently used pitches.
Last night, he showed a significant difference in his delivery and had much better results, but look at the difference in pitch location that backs that up.
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The fastball is way more in control and a far more competitive pitch and the slider is doing what you want it to do by coming in just under the zone. I do see the hangers you're talking about with the curve (he should probably not do that against a better offense) but this is a way different performance than we've seen from him so far.
All that said, there is no way to know if he can do it again next start. Tightening up your delivery and repeating it is one of the hardest things to do in the sport but it wasn't just the lineup that drove that performance last night. He was objectively different. Now lets see if he can do it again.