Hm, let's see.
Lebron, Durant, Kawhi, George, Melo, Hayward, Butler, Gay, Gallinari, Batum, Giannis
Yeah, I'm gonna go ahead and say he's definitely not top 5. You can make a case for Crowder versus a few of the names I just listed, based on a defense, but top 5 is out of the question.
Still, he's getting paid wayyyyy less than the guys I just listed, he's locked up long term, and he's solidly above average.
He's having a really nice year. It's wonderful to see. I dunno if we can expect Crowder to play like this every season moving forward (role players are often up and down, just look at guys like Ariza, Dudley, Carroll, etc). But given his contract, that's just fine.