I really like AJ Klein, he reminds me a lot of a guy the Titans took a few years ago, Colin McCarthy.
He is a playmaker, hard worker with great attitude and motor. The only real knock on him is sometimes he has trouble getting off blocks (what college LBer doesn't) and some question his sideline to sideline agility.
With that said, I'd take him in the 5th no question. He's probably worth more than that though