The problem is that trading for OL mid-season isn't really common, nor is it going to likely result in an upgrade.
OL tend to play better when there's cohesion and chemistry. The Bears have been a makeshift unit all season due to injuries. The injury to Jenkins resulted in them having to move Whitehair from center to guard, where he's nowhere near as good. And just as they get Jenkins back and the interior looks to be settled, Braxton Jones gets hurt, who is their best linemen overall. Not to mention Nate Davis has been in and out of the lineup.
There's just no continuity at all. They need a new center, because even if Whitehair's strongest position is center, he's still not good.