I'm not big on this trade. Keller is roughly equivalent to Cooley, so you're basically giving up 2 starting RBs for one more proven RB. There are ? about how Torain and Lynch will perform in the future. With how common injuries are, I would prefer to have great depth at RB.
Not a horrible trade, but I wouldn't jump at.
I have similar ?s about Torain's trade value (along with a million other folks), so feel free to weigh in on my trade post