Just google "nfl draft bust probability by position".
There's been a ton of studies done on this. OL & DL are the safest early round picks to make. Something about trench guys make them consistently undervalued and/or easier to accurately evaluate. I'm surprised it's even controversial on this forum. And, the Patriots experience under the Belichick regime shows he's not an outlier at all in this regard.
Here are the OL & DL picks in the 1st or 2nd round under Belichick: Richard Seymour, Matt Light, Ty Warren, Vince Wilfork, Marquise Hill, Logan Mankins, Ron Brace, Sebastian Vollmer, Nate Solder, Chandler Jones, Dominique Easley. That is a damn impressive hit rate of pro bowlers & above average starters & longevity.
Now look at the DBs taken in the 1st two rounds: Eugene Wilson, Brandon Merriweather, Terrence Wheatley, Patrick Chung, Darius Butler (no, not that Butler), Devin McCourty, Ras-I Dowling, Tavon Wilson. Not quite so impressive. Not a single shutdown corner.
So, I agree, if a shutdown corner is available at #32 - obviously, take him. But, what is the probability that will really happen?