Add underinflated footballs to the list of incidents giving Bill Belichick a reputation for guile and playing above the rules.

Softer footballs wouldn't explain all of a rout that earned the New England Patriots a spot in the Super Bowl. But it's another example of Belichick's reputation of searching for edges and bending any rules until he gets caught.

Vague injury reports. Spygate. Signing players with intel on opponents. And now, an open NFL investigation into whether the team cheated during its AFC championship win.

"Because it's the Patriots and they have a history, that brings in a different issue," former All-Pro running back Jerome Bettis said on ESPN. "There's some type of culture there that's conducive to cheating and that's a problem."

Team officials on Wednesday did not respond to a request for comment from Belichick, quarterback Tom Brady or team owner Robert Kraft.

Belichick no longer gets the benefit of the doubt among fans and those in football circles, even those who think he's the best coach in the league. Earlier this month, Hall of Fame coach Don Shula called him "Beli-cheat."

It all traces back to a reputation for gamesmanship that blossomed after the three-time Super Bowl winner's last title in 2004.

In 2007, Belichick was fined $500,000 and the team was fined $250,000 and stripped of its 2008 first-round draft choice by the NFL for videotaping New York Jets signals during a 2007 game. At the time, opponents wondered whether he taped practices, too.

Last year, Cleveland Browns coach Mike Pettine suggested Belichick might have gotten a copy of the Jets playbook through Alabama coach Nick Saban, an accusation denied by Saban and then-Jets coach Rex Ryan.

Belichick has signed players days before the Patriots faced their former team, opening up new avenues of intel. Six days before the opener against Miami this season, a 33-20 loss, the Patriots signed safety Don Jones a day after he was cut by the Dolphins. He played nine games for New England before being cut and re-signing with the Dolphins.

Belichick also likes to tweak the NFL on injury reports. For years, he listed Tom Brady as "probable" even though he didn't miss practice and played the games. And he's been known to list close to 20 players on the report, most with minor ailments.

And one week before questions of air pressure, some people questioned whether Belichick was bending the rules in a playoff win against Baltimore by using a four-man offensive linemen formation for three plays on a touchdown drive that helped the Patriots rally from a 14-point deficit. The formation — a backup tight end lined up as a tackle-eligible and a running back lined up as an ineligible receiver split wide — wasn't illegal, only creative and intentionally deceptive.

The NFL continued its investigation Wednesday into whether the Patriots snuck underinflated footballs into their 45-7 win against the Colts. Underinflated balls are considered easier to throw and catch, and the league has strict protocols for air pressure and who can handle footballs before and during games. Each team provides its own footballs for use on offense, which are inspected. Tampering or switching footballs can result in $25,000 fines, or worse.

"We are continuing our review and will provide information as soon as possible," league spokesman Brian McCarthy said.

ESPN reported Tuesday night, citing anonymous sources, that the NFL found 11 of 12 footballs provided by the Patriots were not properly inflated, while balls used by the Colts on offense met league standards.

The issue has drawn strong reaction from players, league executives and other NFL personalities who are debating whether the issue affected the Pats-Colts matchup and the sport itself.

Colts linebacker Erik Walden said on Twitter: "patriots motto 'if u ain't cheating then u ain't tryin'" before following up by saying the Patriots deserved credit for the win.

His teammate Dwayne Allen tweeted, in part: "They could have played with soap for balls and beat us. Simply the better team."

Pittsburgh Steelers President Art Rooney said he wouldn't consider this matter "serious," saying kickers used to manipulate footballs.

"This rule where we use two different sets of balls is relatively new and frankly I'm not sure why we came to this conclusion," Rooney said. "I assume this will be something the competition committee looks at. I think we all should use the same ball and not have each side kind of have their own footballs available to them. That's my view of it."

In Seattle, Seahawks cornerback Richard Sherman said the issue won't have any effect on the Super Bowl, even if it's against the rules. He said he doubts anyone will be suspended or that anything will happen, unlike when the league threatened to keep running back Marshawn Lynch from playing in the NFC championship game if he followed through on plans to wear gold shoes.

"Whatever they did, the risk reward was greater. They were trying to suspend Marshawn for gold shoes," Sherman said. "That really affects the game if you suspend Marshawn for gold shoes. But then you've got balls being deflated and that's the issue."