That was what he struck Inge out on to end the World Series in 06. It's not the best slider in the world, but it's a good secondary pitch for him and it compliments his fastball, curve, and change-up.
I'll never forget that game seven in the NLCS against the Mets.
That catch by Endy Chavez was unreal. I also remember Yadier Molina's home run to put the Cardinals ahead- I waited until I saw the ball bounce around on the ground behind the fence before I celebrated because of that catch. I thought Chavez was going to get that one too! And then Wainwright loads the bases with a two run lead, and I look at his eyes, and I'm thinking- crap he's scared, get the pitching coach out there! Duncan calms him down, and then Beltran gets up there and he struck him out. Before and after that, Wainwright was fine. I think he just got caught up in the moment a little bit for whatever reason.
I also remember all of the New Yorkers literally praying in the stands during the 9th inning, and grown men crying when it was over. I've never seen that before.