Quick n dirty:
I'll go back to 2015, because the more recent guys, we can't tell if they're good or not. These are 1st-teamers, so I'm judging by 1,000 yard seasons or top 5-/10 at their position. Looking at the first team All-American skill position players:
2015
QB - Watson - GOOD in NFL
RB - Fournette - I say very underwhelming, but whatever
RB - Henry - GOOD
WR - Coleman - nope
WR - Doctson - nope
.
2014
QB - Mariota - GOOD, but has regressed and hasn't won anything
RB - Coleman - nope
RB - Gordon - he's been fine, one 1,000 yd season, basic ypc averages, not a top 20 RB
WR - Cooper - GOOD
WR - Higgins - nope
.
2013
QB - Winston - nope
RB - Carey - nope
RB - Williams - nope
WR - Cooks - GOOD
WR - Evans - GOOD
.
2012
QB - Manziel - nope
RB - Ball - nope
RB - Barner - nope
WR - Lee - nope
WR - Williams - nope
.
2011
QB - Griffin - nope
RB - Ball - still nope
RB - Richardson - nope
WR - Blackmon - nope
WR - Broyles - nope
WR - Woods - GOOD - has improved
.
Yes, RBs and WRs who get 700 yds per season are useful and they're making a career. But for every one of those who are considered a "nope" here, there's another "nope" that didn't contribute anything. I don't know how many are injuries, but no, most good college players definitely do not become good NFL players.