Want to change my mind? Show me the numbers. If not, all I am hearing are other people's assumptions.
Not entirely sure why the proof of burden is on the logical argument, but whatever

I was going to test the thesis by going through Spider-Dan's list, but (as pointed out elsewhere) it's not necessarily indicative of the overall picture. It also turns out that's it's a PITA to check. I did the first three:
Ohio State named 3 team captains for the 2009 season and all 3 were drafted (in addition to 1 non-team-captain). (
source)
Oregon named 4 team captains of which 2 declared for the draft. 1 was drafted, 1 wasn't -- out of 3 Ducks drafted. (
source)
Florida named 5 team captain, all of whom declared as far as I could tell. Two of those were drafted (out of 9 Gators picked in the draft). WR Ryan Stamper was injured prior to the draft and was not selected. Has now signed with the Lions. Return specialist Brandon James went undrafted and has been picked up by the Colts. WR Joey Sorrentino was undrafted and hasn't caught on anywhere AFAIK. (
source)
Since I'm not sure what, if anything, this tells us about the overall picture, let's instead examine some other team and see how many team captains they drafted. Let's go with the Raiders first, since they're not exactly known for being a "moral leadership" team...
Raiders 2010 Draft:
Rolando McLain, LB, Alabama, TEAM CAPTAIN (
source)
LaMarr Houston, DT, Texas, TEAM CAPTAIN (
source)
Edwin Veldheer, T, Hillsdale, TEAM CAPTAIN (
source)
Bruce Campbell, T, Maryland, (negative)
Jacoby Ford, WR, Clemson, (negative)
Walter McFadden, DB, Auburn, TEAM CAPTAIN vs Georgia (
source)
Travis Goethel, LB, Arizona State, (negative)
Jeremy Ware, DB, Michigan State, (negative)
Steven Brown, DB, Michigan, TEAM CAPTAIN (
source)
5 of 9. Not too shabby for the RAIDERS...
Several stories around the web note that the 5 of 6 picks by the Chiefs were team captains.
Based on this small sample, I'm still of the opinion that 7 of 8 isn't all that spectacular. Not saying it's not "above average", but if a team like the RAIDERS has > 50% team captains amongst its picks...
I'd wager that less than 25% of the players who got drafted into the NFL this year have that distinction.
That particular wager isn't looking too hot.