It’s less that Cruise has a lot of “embarrassing performances” than that he’s got a lot of easy-to-mock mannerisms as an actor/celebrity. Around the time of the couch jumping incident it became popular to make fun of him as a sort of dorky white guy, with Cruise the actor and Cruise the person blurred together, and he’s never entirely recovered, but I think some of his mannerisms would be worthy of parody regardless of his religious affiliations and celebrity scandals.
I recently rewatched Collateral for the first time in 20 years and his performance in that is totally inconsistent and I don’t think it has to do with him playing a rare villain character for once. It’s like The Best And Worst Of Cruise. He is really scary and seems like a dangerous killer in scenes where he has to kill people, but then there’s goofy Cruisey moments like when he points his gun at Jamie Foxx after killing the first guy he’s supposed to kill and he goes “RED LIGHT MAX!!” or something like that and the “pose” he makes when he does it is totally laughable. Every Tom Cruise movie seems to have at least one moment where he reads his lines too intensely or something and he turns into that Not Tom Cruise impersonator guy who makes fun of him on Youtube. I think I like War Of The Worlds second best and there’s a moment where he yells at his son that never fails to make me laugh.

As TonyV has pointed out, he gets a bad rap though and at least works with lots of good directors who have probably made him seem like a better actor than he is.

I just happily marched off to watch the new Mission: Impossible; it wasn’t all that great, but I’m not adverse to watching movies with the guy in them, $cientologist goofball though he is.