FOXBORO — Bill Belichick has been in the NFL since 1975, so chances are pretty good that by this time in his career, he’s going to run into a former assistant on the other sideline each game.

This week is no exception. Dean Pees is the Ravens linebackers coach — the same Dean Pees who was on Belichick’s New England staff from 2004 through 2009. Pees, who was a lightning rod for criticism in his tenure (especially when he was defensive coordinator from 2006 through last season), was more intimately connected with the Patriots’ defense than anyone other than Belichick.

But neither Belichick or Pees believes that background knowledge will play much of a role this week when the two teams meet Sunday at Gillette Stadium.

“I don’t think it’s too big of a factor,” Belichick said. “We played them twice last year. I think they know us pretty well and we know them pretty well. Every game changes anyway because of dynamics of personnel and just the normal progression of your team from one period of time to another.

“Dean obviously knows us well. I’m sure he knows our personnel and can help their players and their coaches with some of the strengths and weaknesses of our individual personnel or maybe a particular scheme that we run that he’s familiar with. But I think in the end it goes back to the players going out there and playing well and executing well. I think that’s really the most important thing.”

Pees was New England’s linebackers coach in 2004 and 2005 before becoming coordinator for four seasons. While New England’s defense was one of the best in the league at holding the opposition in check — the Patriots were fifth in fewest points allowed last season — a relatively young group struggled in the second half of games (especially on the road), and had trouble creating sustained pressure on opposing quarterbacks.

At the end of the season, Pees issued a statement saying his contract was going to expire and that he had decided not to renew it. However, he became Baltimore’s linebackers coach less than two weeks later, and on Sunday, he will return to Gillette Stadium for the first time as a member of the visiting team.

Pees said that just because he saw most every snap Tom Brady took from 2004 to 2009, that doesn’t mean he knows what New England has in store offensively this Sunday.

“Obviously, I’ve practiced against Brady a lot, but that doesn’t necessarily mean that’s what they’re going to do in the game,” Pees told Baltimore-area reporters on Thursday. “I’ve seen it all, over practice, over six years. I’ve seen every formation, everything that they do, and they keep changing it all the time. So it’s going to be game-plan specific for what we are.

“And so, all I can do is, I think I can help a little more on personnel and what guys can do, and maybe what the shortcomings are, or what they’re not, hopefully. But I don’t think that’s any more than what we do every week. So I think it’s pretty much a normal [week]. You look around the league and you think about all the teams that have somebody on a staff from another team, so it’s like everybody’s got a little bit of input here and there. I don’t think you can make too big of a deal out of that.”

Pees did acknowledge the fact that Belichick and the Patriots have enjoyed great success in games after their bye week — the extra time to scheme has allowed New England to post  seven consecutive wins following their week off, dating back to their last loss in 2002. In addition, they’re 8-2 after their scheduled regular-season bye weeks since Belichick took control in 2000. In all, the Patriots are 14-4 under Belichick after a week off, and have won 12 of their last 13 such games — the lone exception coming in Super Bowl XLII.

Pees has seen Belichick’s post-bye week success get into the heads of several opposing coaches.

“Well, that’s the thing about Bill,” Pees said. “He can do a lot of change, and he can do no change. So it’s going to be whatever he thinks they need to do on both sides of the ball and on special teams to win the game. I’ve been there before where we did a lot of change in the bye week, and there’s times when we didn’t do any change in the bye week.

“Sometimes you self-scout each other, and I can still remember one time we self-scouted ourselves on defense, and I noticed that on first-and-10, I never ran any pressures. And so I told Bill that during the bye week. I said, ‘I’ve studied myself and I’ve noticed that ... I’ve never pressured on first down. I probably should change that.’ And he looked at me and goes, ‘We’re No. 1 in the league in first-down defense. Why?’ OK, makes sense to me. So sometimes you study yourself [and] if you’re doing well, make somebody make you change. Don’t overanalyze.”

Pees acknowledged that while this week will be different — he said it’ll be “like playing golf against my brothers” — the desire to compete and win will be the same as it is every other week.

“It’s always more competitive when you’re going against somebody you know and you like,” Pees said. “It’s like playing golf against my brothers, who I love. I’m a lot more competitive. It’s kind of like you always want to beat family and friends more than you really want to beat somebody else.”