Mejia's angry with himself, no doubt about it. But is he Ted Lilly angry?
Nah, probably now. He is certainly more upset than Shawn Marcum, however:
So, on the Marcum-Lilly Scale of Home Run Anger™, I think Mejia is at 1.5 Clayton Kershaws:
(Mejia GIF from @CrashburnAlley, the others come from the internet. They're everywhere.)