FOXBORO -- There are several reasons why the Patriots and Steelers have maintained an extended level of excellence over the years, but a sizable portion of their success can be traced back to the stable quarterback/coach relationship on each team.

In New England, Tom Brady and Bill Belichick have the longest active relationship between a quarterback and a coach in the league, having started together in 2001. Meanwhile, Ben Roethlisberger has been the starter for Pittsburgh since his rookie year of 2004, and maintained that spot after Mike Tomlin became head coach in 2007.

The Brady/Belichick bond has added up to 116 wins as a duo, which ties them with Don Shula and Dan Marino as the winningest quarterback/coach combo in league history. (For the record, Belichick and Brady needed 139 games to get to 116. Shula and Marino were together for 184 games.) The 116-33 mark is good for a .779 winning percentage. Meanwhile in Pittsburgh, the Roethlisberger/Tomlin combo is 40-19 while together in the regular season and 5-2 in the postseason, a .682 winning percentage.

The parallels between continuity at the quarterback/coach spot and on-field success are no accident. In fact, most teams with a QB/coach relationship that goes back more than a few years have won Super Bowls, like Eli Manning and Tom Coughlin, who have been together with the Giants since 2004 and have one ring. But most of the real success stories have been duos like Tomlin and Roethliserger who have joined franchises separately but learned to make magic together over the course of many years:

•Peyton Manning came into the league in 1998 with Indianapolis, and after linking up with Tony Dungy in 2002, won a title before Dungy stepped down following the 2008 season.

•Green Bay’s Aaron Rodgers was drafted in 2005, a year before Mike McCarthy became the head coach of the Packers. Rodgers became the starter in 2008, and Green Bay would go on to win a title in 2010.

•Drew Brees started his pro career with the Chargers, but joined the Saints and Sean Payton in 2006. They two have been together ever since, and have a title of their own to show for it.

•And in San Diego, after three seasons with Marty Schottenheimer, quarterback Philip Rivers and head coach Norv Turner came together in 2007. Since then, the twosome has been to the playoffs three times in four years, averaged more than 10 wins a season and appeared in one conference championship.

In a league that’s so quick to change -- quarterbacks, offenses, schemes and coaches -- even a couple of years together can go a long way. Before practice on Wednesday, Brady said having the chance to operate in the same system for such an extended period is “great for a quarterback.”

“There are certain plays in our offense that I’ve literally run thousands of times,” he said. “You make a lot of mistakes over the course of those plays, and you learn from them and hopefully you don’t make them again. It’s great for a quarterback to have that continuity with coaching, and obviously the terminology of the plays. It’s been a huge benefit.”

Brady has not only had permanence at the head coaching position, but things have also been relatively stable when it comes to the rest of the coaching staff. He’s worked with three offensive coordinators in 12 seasons (Charlie Weis, Josh McDaniels and Bill O’Brien). Compare that to a quarterback like Drew Bledsoe, who had to deal with three different head coaches and four different offensive coordinators in eight years as New England’s starting quarterback.

“It’s been very important for me to never really change offenses or learn new terminology,” said Brady, who has only played for two head coaches -- Belichick and Michigan’s Lloyd Carr -- since he was 18. “I think we’ve just built on it over the years -- things I learned 12 years ago when I came here.”

For Roethlisberger, the transition from Bill Cowher to Tomlin was eased in no small part because the overall philosophies of the Pittsburgh organization on both sides of the ball have been the same since shortly after the earth cooled. In seven-plus seasons in the NFL, he’s dealt with two head coaches and two offensive coordinators. Roethlisberger acknowledges he’s had it good when you contrast him with someone like San Francisco quarterback Alex Smith, who arrived in the league a year after Roethlisberger and has had four different head coaches and six different offensive coordinators.

“It’s great,” Roethlisberger said. “I’ve always said that I felt bad for someone like Alex Smith out in San Francisco, who I think in about five years had four coordinators, or whatever the ridiculous number was. I think that’s really hard for a quarterback. Any time that you can get familiarity with a coach, with a coordinator, with a play caller, whoever it is, I think it definitely makes it a lot easier on you.”

Tomlin, who has had Roethlisberger miss just six starts since he took over as coach prior to the 2007 season, said Wednesday afternoon that continuity at quarterback “is a big positive,” but added that “you have to guard against getting too comfortable sometimes.”

“It also sometimes potentially breeds a lack of communication or assumptions and that can be dangerous,” Tomlin said. “There are some positives and there are some negatives and you have to weigh on a daily basis.”

“I think the challenges that the National Football League presents on a week in and week out basis is enough to keep it fresh. More than anything, I just guard against assumptions or assumed communication.”

In the end -- like any long-term relationship -- if the lines of communication stay open, success will follow.

“I feel like I have a good player-coach relationship with Tom,” said Belichick. “We have spent, through the years, a decent amount of time together on a regular basis. I think that’s important. We talk regularly during the week about what’s going to happen, how we’re doing it, and then we review what did happen and then we move on to the next stage. It’s a continuous cycle that we’ve kind of been in that routine for a lot of years now.”