Actually I've always thought the blitz worked better against the run than against the pass, nothing fills running lanes like a blitzing linebacker, but the LBs better be aware of who has the ball I have seen blitzing LBs miss the handoff and run right past the guy with the ball (which tends to result in a roughing the passer call as the LB doesn't stop to wonder why the QB is just standing there). Problem with blitzing on the Pats is they have a great short passing game, good enough to get them two rings before they had a legitimate running game, and the short pass is the ultimate nemesis of the blitz. Johnson's pretty smart though, I have serious doubts he'll go blitz happy against the Pats.
The Steelers seemed just as determined to stop Dillon on first down as the Pats were to stop Bettis or Staley. The Pats caught them blitzing a few times and made them pay.