I thought earlier in the season about a thread pertaining to which position turned out the best coaches. We'll get it in the off-season, but for now I'll add John Madden and Les Miles as former OL.
Back to the OP, it's hard to nail this sort of thing down. Some of the lesser known players can be great football minds. Vince Lombardi was hardly HOF material as a player.
I don't mean to hijack this thread, but the whole position thing is starting to interest me. I think the difficult thing to do is to compile a list of all coaches from the past, say, 5 years, and record all of their positions. Then, there's the issue of older coaches vs. younger coaches - someone who played TE 40 years ago might not have the same experience that might lead to coaching as a player who played TE 10 years ago... Anyway.
I'd imagine that DBs are simply more likely to become head coaches, thus why so many successful head coaches were DBs. You probably also have a lot of failed head coaches who were DBs. But, if we are looking at which of our players are most likely to get into coaching, looking at old DBs might be a good place to start.
In that regard and trying to get back to the point of the thread, some of our recently graduated DBs:
Ramzee Robinson, Charlie Peprah, Roman Harper, Simeon Castille, Justin Woodall, Marquis Johnson, Javier Arenas, Mark Barron, Kareem Jackson, Tyrone King, Wes Neighbors, Cory Reamer, Rashad Johnson, ...