Paul Chryst said on Wednesday that team captains were voted on by the team following Tuesday's practice.
For Grigsby, while there were a number of seniors that could have been chosen from, Chryst said it's not surprising due to his work ethic.
"Obviously, it's more than just camp," Chryst added. "The way he approaches the game is just outstanding. He's worked at his game and his body. He, like all the players here, has grown as a person throughout his career."
Clemmings wasn't even a starter two years ago, and made a move from the defensive line to the offensive line last year, becoming a full-time starter, now into a leadership role as captain.
"We talked when he came off the field at South Florida (the 2012 regular season finale)," Chryst said. "His uniform wasn't dirty, and he said, 'Coach, I'll do whatever I can for this team.' You don't have a better example of that than T.J."
Here is Chryst's complete post-practice interview from Wednesday.