They talked about it a bunch here on Nashville sports talk today. Apparently it isn't an illegal hit (basically just a cut block), just not something guys generally do away from the ball. Blaine Bishop, who played for the Titans, didn't care for it at all though.
it's a gray area...you're not supposed to go below the waist on the side or behind.
the problem for me is the league created this by eliminating the defenseless hit and the hit to the head.
and talib is not the guy to get a quote from re: dirty play...that dude shot at his own family b/c of sh t on the field.