Sometimes, coach Chuck Pagano sees the tough, stout, dominant Colts defense he envisioned.

Other times, he sees a defense that is frustratingly unrecognizable.

The inconsistency is as perplexing to fans as it to Colts coaches and players, and they have six weeks to figure out what's wrong.

"It's up to us to execute," defensive end Cory Redding said Monday, less than 24 hours after an embarrassing 42-20 home loss to New England. "Look, it's a tough pill to swallow, but let's make it clear -- we've got to go out and play winning football."

On Monday, there was more bad news: Running back Ahmad Bradshaw, who was having a terrific bounce back season, was diagnosed with a fractured left fibula. Pagano wouldn't say how much time he would miss or whether the Colts would place him on season-ending injured reserve until doctors had some follow-up exams.

Redding, a 12-year NFL veteran, needed eight seasons to reach the playoffs. He missed out on a Super Bowl ring when he deiced to leave the Ravens in 2012 and follow Pagano to Indianapolis in 2012. He's dealt with coaching changes, injuries and the ignominy of playing for the only 0-16 team in league history, the 2008 Detroit Lions.

So he understands all is not lost. Indianapolis (6-4) still leads the AFC South by one game and has only two teams with winning records left on its schedule.

"It's definitely frustrating because we're a good defense," injured defensive tackle Arthur Jones said. "We just have to be consistent."

That has been the biggest problem.

While Ben Roethlisberger's six touchdown passes in a 51-34 thumping could be excused as an aberration because the game was played in Pittsburgh and the Colts lost their top cornerback, Vontae Davis, early in the game, there's no explanation for what happened Sunday night.

After New England rushed for 234 yards in a 21-point blowout in January, coach Bill Belichick stayed on the ground against Indy's revamped defense and rushed for 244. Indy couldn't blame this one on the weather, injuries, the Patriots having an extra week to prepare or even Andrew Luck's interceptions. Instead, New England (8-2) came into Lucas Oil Stadium and beat up the Colts on their home turf in a game with playoff implications.

"We're going to go back and look at the tape and try to figure out exactly what went wrong as far as stopping the run and playing better in the red area and those type of things," Pagano said after Jonas Gray ran for a career high 199 yards and four touchdowns Sunday night.

A few weeks ago, it looked like Indy's three-year rebuilding project was about to pay big dividends. The Colts gave up 13 combined points against two playoff contenders, Baltimore and Cincinnati, and never allowed those offenses to get in sync.

Then came the defensive debacle in Pittsburgh, another stout performance against the Giants and Sunday's loss after a bye week.

"You know what, the Patriots outplayed us last night," Redding said. "But you've got to move on."

Notes: Tight end Dwayne Allen has been listed as day-to-day with a right ankle injury.

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