I'm not disputing that, but if you noticed on the blitzes Steelers Depot showed, the Steelers were playing zone behind them, and on two of three of them both Harrison and Dupree were in coverage. To me, if you want to maximize the chances of a blitz being successful, you should probably have at least one of your best pass rushers as part of it.
Plus, half of those technically were not blitzes, as there were only four defenders going after Brady.
It just seemed like Tomlin and Butler game planned to sacrifice pressure for coverage, as that was probably the most three man rushes they've used since the first month of the season.
real stupid time to go away from what has worked during the winning streak