ALLEN PARK -- Matthew Stafford was third in the NFL in passing yards last year. He was sixth in completion percentage and QB rating, and yards per attempt too. He was second in deep passing.

Almost any way you measure it, the longtime Lions quarterback was among the best in the game at his position.

But he was not perfect.

In fact, when it came to losing fumbles, he was the worst in the league. Stafford coughed up the football 11 times overall, and lost seven of them. That matched Tampa's Jameis Winston and Houston's Tom Savage for most in the NFL.

As he sets course for 2018, Stafford knows he must improve his ball security.

"I can always be better," Stafford said Tuesday as Detroit continued its offseason program. "Obviously, I think I turned the ball over too many times last year, got the ball knocked out of my hands or threw it to the other team too many times. Every offseason, you're looking at those and hating watching them again and trying to find ways to make sure they don't happen again. That's a huge one, obviously -- a big one always in the NFL is turnovers, so I can always be better doing that."

Stafford did a decent job through the air, where he threw 10 interceptions for the second straight season. That was fewer than guys like Russell Wilson, Matt Ryan and Kirk Cousins, even though he attempted more passes than all of them. He threw a pick on 1.8 percent of his attempts, which was top 10 in the league.

Given how much pressure he faced -- he was sacked 47 times, which was more than everyone except Jacoby Brissett -- that's not bad. But all that pressure did produce too many fumbles.

Stafford had multiple fumbles in four games last year -- Carolina, New Orleans, the home game against Minnesota and Baltimore. Notice what those games have in common?

The Lions lost all of them.

When Stafford fumbled the ball once or not at all, Detroit was 9-3.

There's still no better predictor of wins and losses than turnovers. Stafford continues to do a solid job through the air, especially given how much he has to take to the air because of the troubled ground game. But the fumbles were out of control last year, and that will be a focus moving forward.