PITTSBURGH — One AFC championship game lost, then another and another, and another still.

In Jerome Bettis' mind, the Pittsburgh Steelers' long list of AFC championship game defeats in a relatively short period of time can't be blamed on being too tight while playing at home, inadequate game planning by coach Bill Cowher's staff or a lack of talent.

The real culprit?

"Turnovers," he said Wednesday. "Turnovers."

Bettis has been around for only three of the four AFC title game defeats since January 1995 — to the Broncos (January `98) and the Patriots (January 2002 and 2005). But each followed a similar pattern: The Steelers underachieve at home mostly because they turn the ball over in key situations.

Kordell Stewart threw three interceptions and lost a fumble as the Steelers couldn't hold a 14-7 lead in that 24-21 loss to John Elway's Broncos at Three Rivers Stadium. Bettis ran for 104 yards and one TD, but seldom saw the ball after Elway threw two scoring passes in the final two minutes of the first half to put Denver up 24-14.

"That's the one you wish you had back because there was no reason for you to have to throw the football like that," Bettis said.

Stewart was intercepted three more times and the Steelers lost a fumble in their 24-17 loss to New England in 2002 that turned on Antwan Harris' 49-yard return of Kris Brown's blocked field-goal attempt. And the Steelers had five turnovers, including three interceptions by Ben Roethlisberger, as the Patriots beat them 41-27 last year after Pittsburgh came in 16-1.

The Steelers' tendency to turn the ball over in their biggest games must be a concern going into Sunday's AFC championship game at Denver. The Broncos had 36 takeaways during the season, second only to the Bengals' 44 in the AFC, and they forced an uncharacteristic five turnovers by the Patriots last week to end New England's chances of winning a third consecutive Super Bowl.

"Defensively, they can pressure you," Cowher said. "You're going to see all 11 guys at the line of scrimmage sometimes — you're going to see the safeties and everybody up there. You better be able to protect, you better be able to handle the pressure, you better be able to sit in the pocket at times. You may have three-and-outs, you may have to punt, just don't make a bad play."

Roethlisberger's ability to protect the ball — he has five touchdown passes and one interception in two road playoff games — has allowed the Steelers to mount long drives and open up their offense, something they've almost never done in the postseason under Cowher.

Roethlisberger was 6-of-7 on an 84-yard touchdown drive that opened their 21-18 upset victory Sunday in Indianapolis, creating the momentum the Steelers never had in their earlier 26-7 loss to the Colts.

Cowher never would have put that much trust in his quarterback so early in a game a year ago when, despite his 13-0 regular-season record, Roethlisberger was shaky and mistake-prone while throwing five interceptions in two playoff games.

This week, Cowher said, "We are going to be able to go as far as he can take us."

"I have no problem with that because I want to come out and take care of the things I have to deal with," Roethlisberger said Wednesday. "If you don't turn the ball over and you do the things you're supposed to do, you give your team a better chance of winning."

Roethlisberger's 124.7 passer rating is easily the best in the playoffs. His record this season (11-3) isn't as good as that a year ago (14-1), but wide receiver Hines Ward said he's so much better there is almost no comparison.

"It's night and day," Ward said. "Last year, it was overwhelming for him sometimes. I really think he got caught up a little bit with the notoriety and magnitude of the game. This year, he understands the offense and is starting to trust his guys. He's not really putting it on his shoulders."