Looking at freshman that put their names in the draft pool and then ultimately withdrew in recent years (dating back to 2016):
There have been 5 players to withdraw from the draft and ultimately get selected in the first round later on as far as I can tell:
- Tre Mann
- Quentin Grimes
- Obi Toppin
- PJ Washington
- Caleb Swanigan
I don't believe any of them had particularly high draft stock at the time when they withdrew. Grimes was expected to be like a lottery pick as a freshman but was ultimately a disappointment and I think had to rebuild his draft stock with his strong sophomore season to get back into the first round. Andrew Nembhard was also the first pick of the second round, so he nearly qualified.
A few recent examples that went the other way:
- Rawle Alkins - I believe was projected to go around with Judah currently is, maybe earlier. Ultimately returned for his sophomore season and went undrafted.
- Jontay Porter - He was a projected 1st round pick. Ultimately returned to school and went undrafted.
- Yet to be drafted, but Terquavion Smith was a projected 1st round pick last year and is currently all over the place; the consensus big board has him at #29 right now but I've seen reputable mocks with him dropping as far as the 50s. Likewise, Harrison Ingram was on the fringe of the first round last year and has now transferred to UNC to try to rebuild his draft stock after showing modest at best improvements this season.
- Marcus Bagley was a projected late 1st or early 2nd round pick after his freshman season; after returning, he has played in 5 games the last two years and I do not believe he is really viewed as a draftable prospect anymore.