It was a tale of two halves for the Buffalo Bills' offense Sunday.

In the first half, the Bills moved up and down the field against the Dallas Cowboys.

In the second half, the offense moved nowhere. What was worse, it made two deadly turnovers that led to 10 Dallas points.

The result was a 30-13 loss to the Cowboys, the Bills' fourth straight Super Bowl defeat.

"We knew coming into the game that when you play an awfully good football team like Dallas you have to minimize your mistakes," said center Kent Hull. "We lived and died by turnovers this year. Our defense got us big turnovers all year, and we capitalized on them. That was what cost us today."

The Bills' three turnovers led directly to 17 Dallas points, the margin of victory.

The Bills gained 216 yards in the first half and moved the ball on four of their five possessions. In the first 30 minutes, the offense produced an 80-yard touchdown drive, two field-goal drives and a 53-yarder from its 1-yard line that reversed field position.

However, it was all downhill in the second half after Thurman Thomas fumbled on the third play from scrimmage in the third quarter, and James Washington returned it 46 yards for a touchdown to tie the game, 13-13.

"We had them pretty tight coming into the second half," said Hull. "They might not admit that, but they had to be a little tight. We were getting the ball to start the second half. If we can mount some kind of drive -- whether we score or not -- but get the field position changed to start the third quarter, I think it's a different ballgame. To turn it over like that and then get seven points out of it (for Dallas), it's a huge, huge momentum change."

"We had that one turnover, and it set us back," said guard John Davis. "We could never get our game plan going again after that. We felt at halftime if we could keep our game plan going we'd have a chance. If we could keep the pressure on them by running the ball, we could keep the passing game going. We just never got our running game back on track in the second half. When we can't run the ball, we're not very effective."

The Bills were killed by poor production on first down in the second half.

On the series after Washington's fumble recovery for a TD, the Bills went three downs and out. Thomas gained 2 yards on a first-down run.

On the next series, the Bills drove 17 yards and punted. A first-down screen to Kenneth Davis lost 8 yards. A long first-down pass for Don Beebe was incomplete and a Davis first-down run lost 3 yards.

On the next series, Davis lost 4 yards on a first-down screen. On the Bills' fifth possession of the second half, Jim Kelly threw an interception on the third play.

The Dallas secondary came up to help stuff the screen passes.

"We've been successful the past two weeks on screens, and today they did a good job reading them," John Davis said.

"I've never seen anybody react to the screen pass the way they did today," Hull said. "They must have had some kind of read on it. When a 300-pound lineman starts chasing 190-pound defensive backs in a foot race, you know who's going to win that one."

The lack of success on first downs put the Bills in third-and-long, must-pass situations.

"They were using a little more safety support on the run early in the second half," Hull said. "Once they got up 14 points, the threat of the run was nonexistent.

"After the momentum changed, we just got a little bit one-dimensional. We were forced to. We had to put the ball in the air and get some points. I think when you do that you see the best of the Dallas Cowboys' defense. They have a lot of team speed. They just keep bringing people off the bench who can rush the passer. It gets awfully tough."

"I felt our guys gave it all they had over 60 minutes," said tackle Howard Ballard. "I don't think we were able to overcome a few mistakes, which a good football team has to do. The Dallas Cowboys made some mistakes in the first half, but they were able to overcome them. We just have to congratulate the Cowboys."