Coincidentally, in his five starts in June, he had an ERA of 3.82. He also had a 3.82 ERA in his first five starts (of 6) in May. So he's been consistently inconsistent all season, putting together a string of a few starts where it looks like he's turned a corner, and then regressing for a few starts.
for the fun of it, I resorted his starts this year by runs allowed. I could have done it by earned runs, but I don't like excusing blow ups after errors when you are talking about a guy who is supposed to have been top of the rotation. He has had 14 starts where he's given up 3 or fewer runs. all but 2 were 6 innings, and the 2 others were 5. Call those good / acceptable starts. He's had six 4-run starts, with one 7 innings and the rest less than 6. I/M/O, only the 7 inning start was OK pitching, and perhaps the 5.2 inning, 4 run, win vs. the Os was just pitching with a lead and not blame-worthy. That leaves two 5-run starts, seven 6-run starts, and one absolutely jaw-dropper 10-run start. Two were immediately after the all star break and one on 7/1 (daggers after the good June), two were in his first starts of the year coming off the COVID shut down (including the 2 run, 10 inning fiasco that poisoned his ERA forever), and 4 were in a lousy stretch of 5 starts in August. The outlier is his one bad start in September (9/18 home v Rox).
I'll give him a slight pass on the first two starts of the year. The MO now is to give guys some minor league appearances before bringing them back after a COVID shut down, so there was an element of letting him take his lumps to those games. Beyond that, he seemed to have his act together the first 3 months. His ERA always was bad due to his first 2 starts, but he wasn't pitching badly before July. His blow up seems more in July and August, with 8 lousy starts (including the 4 runs in 5 innings on 7/29, break up the Nats afternoon), 2 good ones, and one acceptable one (4 runs in 7 innings).
I think that, rather than say he was erratic, it seems more he hit an awful stretch in July and August. I don't know what that means, TBH. On the bright side, it does not seem to be a precursor to needing arm surgery. Velocity is fine. Maybe there was a specific, non-health issue impacting the middle of the season that has been mostly fixed? There was FG speculation about his release point, but other than that I've not heard much.