Well, no reason to IR him until the roster spot is actually needed.
As for the $13 mill, I don't think they're gonna find any FAs that would turn this season around anyway. The season is basically tanked for now. I'm not a "suck for Luck" kind of guy so I'm not rooting for losing just to improve draft position. I never do that. Never. That money rolls over to next year, and without a #1 pick, I suspect it will come in useful in free agency or trade talks.
No, what this team needs to do is dig down and find their hearts and do their best to finish this season as strong as possible. The 'help' they need to find is within, not from outside. There will be turnover this off season and the guys better be thinking of their future by proving to the coaches that they're worthy of bringing back next year, or at least putting up some highlight films for their future evaluations.
If the team were to spend money, I'd look to CB, and there probably isn't any help on the market there, either.