Why 91 On The Steelers Roster?

I was asked via email why the Steelers now have 91 players on the roster. That 91 really is a floating number. NFL teams are only allowed 80 signed players on a roster at any given time. You see, the Steelers drafted 10 players, but none of those 10 players are under contract yet. The Steelers have now signed 9 undrafted free agents after today\’s signing of Bradley Vierling. As the draft picks are signed, one of the undrafted players or offseason signed free agents will be released to make room. I know what you are thinking though, numbers still add up to 81 though. Quarterback Ben Roethlisberger is not allowed to participate in the Steelers offseason activities until he completes the evaluation and is cleared by the league. The Steelers have been granted an extra roster spot I am sure until he is cleared by the league. This would then be the extra player that gives the Steelers 81 players under contract right now.