As reported on Monday and on Tuesday, Cody Grimm has been placed on IR. His leaving would have given Ahmad Black the chance to make the roster, but the Bucs instead decided to promote tight end Collin Franklin from the practice squad. They didn't need to add another safety to the roster: with Sean Jones, Larry Asante, Corey Lynch and Devin Holland they have plenty of depth at the position already.
The addition of Collin Franklin is a little puzzling, though. The Bucs already have three tight ends on the roster, but third tight end Zack Pianalto was listed as 'Did Not Play' in two out of three games. If the Bucs aren't even using their third tight end, why would they need a fourth tight end who did not stand out in the preseason?
Maybe the Bucs want to start running more three tight end-sets, or perhaps they felt that Collin Franklin was about to slip out of their grasp.