I think it's a great idea.
In fact, I would go a step further and introduce Jersey numbers -1 to -20 for underachieving, untalented or lazy footballers on the roster. The further away from zero, the less valuable or respected the player....for example:
-3...Marcel Dareus
-7...Russel Bodine
-16...Kelvin Benjamin
In fact, I'm logging on to Fanatics.com to pre-order my Vontae Davis -20 jersey right now!!