Quick take: Most teams rotate their defensive linemen to keep them fresh. But the Bucs didn't do that with McCoy and Clayborn. The theory behind that was that, even when a bit winded, they were substantially better than their backups. The rookie Gholston got a lot of playing time in the second half of the season.
Quick take: The Bucs played David as much as they possibly could because he might be the best player on the team. Some of Watson's snaps came at defensive end as the Bucs experimented with him at that position late in the season.