I don't think I can really judge him having "fight" on defense from college, his role was too important on offense to even allow him to be THAT committed on D. I'm just saying his size won't be as significant of a problem as some make it out to be. It's more on effort than physical limitation.
CP wasn't always a good one on one defender, he racked up a lot of steals in college but he wasn't super aggressive on D. His team overall was bad defensively. He had better instincts than Trae does on D but it goes to show that size isn't the end all be all with defense for PGs.