That works sometimes and sometimes not so much. Look at the Eagles and McNabb. Nobody would argue that the Redskins are weaker with McNabb running Shanahan's offense than they would have been with Campbell. And not all the time you're giving up a player you straight up think is bad. You might not have room on your roster for a WR that's only great at special teams (think Kelley Washington) but a team that's not as deep is just going to get stronger by having him.
I dont know that.
Why couldnt it be that the Eagles think McNab is done? He is beaten, battered and oft-injured.
This is the point I am making.
If the Eagles looked at the situation and said that at this point in his career McNab is no longer worth the contract he will expect, that they havent won with him yet, so at this point in his career will they ever, and that they would be better with a draft pick than keeping thier franchise in his hands, breaking the bank, and not getting a pick for him.
Clearly they thought something like that.
If they figure they are better off without him then who ever they trade him to will therefore be worse off with him.
Sure, he may be better than the guy they are puttng in at QB, but the Eagles made the decision that he would be worse for their franchise than a 2nd rounder (or whatever they got) whether they are right or wroing, they are operating from that belief, so they just weakened an opponent.
If the trade lets the Redskins improve to 8-8 then watch McNabs skills deteriorate and his injuries mount and they never win a championship, much less a division, or a playoff berth, the trade did not help them even if with Campbell they would have been 5-11 this year.
In this case, its long term pain you are inflicting on the rival.
By the way, the thought process I attached to the Eagles is pretty much the way I see this one playing out, and in the long run, the Redskins would have been better using a 2nd on Jimmy Claussen. At least if he fails they wont have the next 3-5 years bound to him.