Yeah, he just slid a bit too fast. his stick is in good position to take away the pass until the last second then open up the lane. Larkin should have been back covering and the timing would have worked out.
Anyway, the next play in the NHL.com highlights Green does a good job covering a 3-on-1 so he learned from the mistake, took away the passes and let Howie play the shooter.
I agree with this, but you gotta give it to Kopitar as well. He's a really good player and made a great play. Most players don't do what he did there.