ALLEN PARK -- The Detroit Lions blazed to a 5-3 start this season, but the second half is off to a rocky start.

This shouldn't be a surprise.

Detroit, after all, is notorious for its late-season flops under coach Jim Schwartz. It has not posted a winning second-half record in any of the coach's first four seasons here.

Matthew Stafford, shown directing Detroit's offense during Sunday's game against Tampa Bay, says turnovers are to blame for the Lions' two-game losing streak.

The Lions (6-5) have lost two of three in the second half this year, after holding fourth-quarter leads in both games, and is limping into the Thanksgiving Day game Thursday against Green Bay (5-5-1).

Detroit is frustrated because it thought it had learned from its previous swoons. Instead, they seem burdened to repeat history.

What's the culprit?

"For us lately, it has been the turnover margin," said quarterback Matthew Stafford, who threw four picks in a loss Sunday against Tampa Bay. "It's the No. 1 stat in football. We turn the ball over and don't get any back, it's tough to win, and we understand that.

"We got to be better with the football."

Detroit committed 13 turnovers in its first nine games, with a plus-two turnover margin, and was 6-3. It has committed eight turnovers in the past two games, with a minus-eight turnover margin.

It lost both games, to Pittsburgh and Tampa Bay.

Stafford was the main culprit against Tampa Bay, firing four picks, though the final one -- which cost Detroit its last shot at a comeback -- wasn't on him. The pass slipped through the hands of Calvin Johnson.

But he's culpable for the other three, and he knows he has to be better -- though he doesn't plan to be any less aggressive to avoid mistakes.

"I'm doing my team and myself a disservice if I throw one that gets tipped and falls in another guy's arms, or make a bad decision, and I go into a shell," Stafford said.

"This offense is built around making plays, and I'm a big part of that. So I got to make sure no matter what happens on the play before -- whether I throw a touchdown or I throw a pick -- I throw it just as confident the next time."

Turnover margin, of course, is a two-way stat. While the offense is turning over the ball too frequently, the defense could do a better job of forcing opponents into mistakes.

Detroit was among the league leaders in turnover margin through the first month of the season, but has slid to 18th at minus-two.

"We need to get back to getting some turnovers on defense," Schwartz said. "Early in the season when we have done well we have gotten the ball and we missed a couple opportunities against Pittsburgh. We didn't have very many opportunities last week, but that's something we need to come back to of coming back out of the plus side of that turnover ratio."

Detroit is reeling, but Schwartz says it's too soon to say this team's collapse will be akin to those of the past few years.

"I think it's too early to say we've struggled in the second half of this season," Schwartz said, after his team's 1-2 start to the second half. "We still have a long way to go. We did struggle in the second half of last year. A couple of years before that, we finished really strong. The playoff year we had to win a couple games late to be able to qualify for the playoffs.

"The story of our team isn't going to be written in the first half, it's going to be written in the second half. It is going to depend on what we do. We need to be able to stop this two-game skid. We need to be able to come out with a win."