If they were going defensive tackle here, I'd have expected Alabama's Jesse Williams, who'd be a smoother fit in the 3-4 sets that everybody thinks Chip Kelly and Bill Davis are going to run. Logan profiles more as a 4-3 defensive tackle, which could make him more of a rotational player on the Eagles' defensive line. That's not necessarily a bad thing, especially in the third round, and Logan is known as a smart, high-character guy who likely would respond well to the instruction required to learn different roles.
Logan's production wasn't the best in his final college season, but obviously Kelly sees something he likes if he's taking him here with guys like Williams and Johnathan Jenkins still on the board. Maybe he can play nose tackle or the 5-technique position on a 3-4 line. Maybe he just helps them with interior pressure when they do go to 4-3 looks. Again, third round. Take the guy you like.