Terry Bradshaw
Bradshaw won four Super Bowls with the Steelers but he also caused the franchise a lot of problems. These were unintentional but came about because he held on for too long. Injuries marred the final couple of seasons of his career and meant that Pittsburgh didn’t enjoy the best version of him.

This was a shame because he was brilliant during his prime. Furthermore, he retired on short notice without giving the Steelers time to make a succession plan. They missed out on Dan Marino because they thought that Bradshaw was going to continue playing (via Bleacher Report).