How can a (now) defensive player BLOCK illegally? Chop the knees out from under his own guy trying to stop the interception from scoring? I am not saying that poor officiating was the only reason the Steelers won, but it was not insignificant.
The idea (and remember I disagree with this, but I did read up on it after the call went against the Steelers twice) is that any engagement with a non-ball carrier is some form of block (like maybe you're trying to knock him down so somebody else can make the tackle). And because the would be tacklers in all three cases went low and had to go through a blocker to make the tackle that makes those hits on the blocker illegal personal foul low blocks. Again I don't agree with it, but how they called it in the SB is consistent with how they called in the regular season (interestingly those are the only 3 times all season I've seen it called, twice against the Steelers and once for).
Looks like someone may have gotten to the officials.