I would have went with Wheeler. I'd agree Burnes was more dominant, but I don't think his advantages in rate stats should offset Wheeler's advantage in IP (213.1 to 167). I think that inning advantage is even more importantin today's game where pitchers don't really go 6+ anymore and 200 inning pitchers have become an endangered species.
What do the playoffs have to do with the CYA? This is literally a pitcher for the best pitcher in the AL/NL, not "most valuable". That should have zero bearing, and any playoff performance doesn't factor into these ballots anyway since they're submitted before the playoffs start.