FOXBORO -- It may not be long before Patriots quarterback Tom Brady tells Steelers coordinator Keith Butler to "study the rule book and figure it out."

Butler made an appearance on Steelers.com's Coodinators' Corner show this week and hinted that the Patriots do things that border on illegal, seemingly referencing their use of odd formations in the Divisional Round of the playoffs two seasons ago as an example.

"I don't think they're doing anything special," Butler said when asked why it's so difficult to prepare for the Patriots offense. "I think sometimes they do things outside the box sometimes, you know, that might be on the edge of being legal or not legal.

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"They've done a couple of things in the past . . . putting an offensive tackle out as ineligible but he's not really. And so sometimes the emphasis by the NFL in terms of what they call and what they don't call, they use that a little bit. And they've been accused of doing a lot of things. But the thing we've got to do is ignore that and play, and hopefully we can give them something they haven't seen from us."

After the Patriots ran their unusual formations against the Ravens in January of 2015, Baltimore coach John Harbaugh insisted that no one had ever seen those formations before, and he was certain the league would look at their legality. Reacting to Harbaugh's comments that night, Brady defended his team's tactics.

"Who knows? Maybe those guys gotta study the rule book and figure it out," Brady said at the time. "We obviously knew what we were doing and we made some pretty important plays. It was a real good weapon for us. Maybe we’ll have something in store next week."

Brady added: "I don’t know what’s deceiving about that. [They] should figure it out."

In the aftermath of the game, the league was open about the fact that New England's formations were, in fact, legal. However, the following week, the NFL's head of officiating Dean Blandino pointed out that Nate Solder's touchdown grab in the AFC title game should not have counted due to an illegal substitution call that was missed.

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The Patriots have yet to run much in the way of formational trickery this season, save for an alignment in Week 5 against the Browns in which Solder was lined up as the left guard next to center David Andrews. On the opposite side of the formation Joe Thuney lined up outside right tackle Cameron Fleming as a tight end. That play resulted in a short LeGarrette Blount run.

Butler added that, "If we're going to beat them, we can't get beat mentally, either, in terms of making mistakes. We can't make mistakes -- mental mistakes. And we have to tackle. If we can do those two things, that will increase our chances of winning immensely."

You can listen to the full interview with Butler -- during which he calls Rob Gronkowski more of a receiver than a blocker and Julian Edelman "more of a possession receiver" -- right here.