Ravens coach John Harbaugh is very cautious about saying anything that might be regarded or interpreted as criticism of officiating.

So it’s no surprise that Harbaugh declined to air his thoughts on inside linebacker Ray Lewis’ helmet-to-helmet hit on Pittsburgh Steelers wide receiver Hines Ward that didn’t get flagged or Pittsburgh free safety Ryan Clark’s helmet-to-helmet hit on tight end Ed Dickson that did get called.

“I’m probably not going to get into that conversation right now,” Harbaugh said the day after the Ravens stunned the Steelers, 23-20, Sunday night. “I mean, it’s tough. There’s no doubt about it, it’s tough. It’s fast and it’s physical and all that, but the rules are in place for a reason, and that’s the way it works.”

But Harbaugh did make a veiled reference to the holding call on rookie wide receiver Torrey Smith that wiped out running back Ray Rice’s apparent 76-yard touchdown run on the first play of the game.

“As far as the running game, I think obviously, the numbers would have been a lot better if the first one hadn’t been called back, which was very well blocked by everybody on the play,” Harbaugh said, drawing laughter from the assembled media.