I would argue this. He hasn't had 2 solid postseason starts in his career. He's had one. And 2 ok-to-mediocre starts is really generous as well. The guy has started 5 playoff games and has recorded more than 15 outs once. That is the one solid start. In the only other start where he recorded 15 outs, he gave up 10 baserunners and 7 runs. That's a lousy start.
In the other three starts, he has gone:
4 IP, 1 H, 4 BB, 2 ER, 5 K - this was game 1 of the ALCS in 2018. I don't consider 4 IP and 2 R an ok-to-mediocre start, but I guess you could call it that?
4 IP, 5 H, 2 BB, 3 ER, 7 K - this was game 1 of the WS in 2018. Again, I don't see how 4 IP and 3 R is an ok-to-mediocre start. It's a 6.75 ERA and making your bullpen throw 5 innings. From your "ace".
1 IP, 4 H, 1 BB, 5 ER, 2 K - last night, total dumpster fire.
He's been better in relief, but even so, gave up that huge HR in game 4 of the 2017 ALDS. His line that day was 4.2 IP, 4 H, 0 BB, 2 ER, 6 K. He was good... until he gave up the game winning homer.
He has yet to have a great playoff start.