One year ago, Joe Burrow was a Day 3 pick.
It wasn't because he was hiding out in the FCS or some poor Group of Five school. It wasn't because he hadn't really been a starter yet, as was the case with Cam Newton and Kyler Murray. It wasn't because he had unorthodox traits (e.g. release, height, runner) that traditionalists couldn't get beyond, as was the case with Phil Rivers, Kyler Murray, Robert Griffin, Lamar Jackson, etc.
It was because he didn't look that talented, nor all that productive. He had been a full year starter at one of the premier programs in the country...and he didn't look compelling.
So I think you'll have to forgive some people like Slimm who take Burrow's rating WAY THE HELL UP from what it was in 2018, but don't quite take it to the level that makes everyone happy (#1 overall).
I think he's explained himself pretty well on this topic. Burrow doesn't have a ton of arm talent. He was older than the guys he competed against in 2019; a graduate student with virtually no course load and nothing but time to watch film with Joe Brady all day. He had a spread offense tailor-fit to him with 5-out on virtually every play, run at a HUNH pace, with one of the finest OLs in the country, one of the finest RBs in the country, and probably the best WR pair in the country. He achieved great things in a great situation. A year before that, with nearly the same surrounding cast, but a less opportune offense, he was worse than Jake Fromm...by a comfortable margin.
I would certainly have Tua Tagovailoa above Joe Burrow. I have not yet decided about Jordan Love.