His shot selection was awful in college-- only shot 33% from 3 and under 40% overall against Tier A competition his sophomore year, not to mention all of the ill-advised contested mid-rangers he'd clunk in iso-- and he's undersized for conventional NBA shooting guard wisdom. Elite athlete, elite defender... but seemed more like a scrappy guard off the bench or the kind of guy who stuffs stats on a bad team more than a guy who stars for a playoff team.

Before the combine, he was expected to go in the 20s. (Source, among others: https://web.archive.org/web/20170401024051/http://www.draftexpress.com/nba-mock-draft/2017/) The draft comparisons I saw at the time were, for best case scenarios, names like Avery Bradley and Eric Bledsoe-- both of whom were picked in the late teens out of college IIRC. And both of them had better college seasons than Mitchell's best.

It's really not that surprising considering what he did in college that he got picked where he did. What *is* surprising is how far he's come in such a short period of time.