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Lions quarterback Matthew Stafford fires a pass during last week's mincamp.

(Mike Mulholland | MLive.com)

ALLEN PARK -- Matthew Stafford was so good during stretches of the Detroit Lions' offseason program, not even a sloppy final day could spoil it.

"I mean, it's obviously always a work in progress," the quarterback said after minicamp wrapped up Thursday. "You're always trying to find new ways to get better.

"But there's no question we've taken strides forward this spring."

Stafford is right. There's little doubt at this point the offense has made progress.

It's hard to tell how much, when everyone's wearing shorts. But the growing efficiency is unmistakeable, and from Stafford in particular.

There was one practice last week where he put only two balls on the ground during team drills -- and safety James Ihedigbo was flagged for pass interference on one of them.

Coach Jim Caldwell is so encouraged by the progress, he believes Stafford's completion percentage will spike in 2015. And that's after Stafford completed 60.3 percent of his passes last season, the second-best clip of his career.

"He's improved," Caldwell said. "He has a better feel for the system. You can see our timing's better, receivers have a better sense of the routes that they're running. All around I think we've made some improvement."

As for what he expects Stafford's completion percentage to be in 2015, Caldwell said, "an improvement from where he was last year."

The offense looked to be ahead of the defense during most of minicamp, with the exception of the final day, when Stafford completed just 9 of his 15 passes and threw one interception. (Though he was also hurt by drops from Corey Fuller and TJ Jones, among others.)

Now the key is to maintain that forward momentum during the six-week break.

Stafford spends much of his offseason in Atlanta, near where Calvin Johnson makes his offseason home. They intend to hook up for some routes, and tight end Eric Ebron, whose development -- or lack thereof -- will be a major factor in the offense's fortunes, could join them

"I think it's big," Stafford said. "At some point we'll get together. I'm obviously in Atlanta quite a bit, so Calvin is right there and I'll throw with him some. But try to find a way to get together with some of the other guys as well.

"We go away, and we come back in great shape. But there's no substitute for running routes, for a receiver, and catching a ball from the guy you're going to be catching balls from in the season. And there's really no substitute for me. Throwing to a spot, or throwing to somebody who isn't on our team (isn't the same). It just isn't as beneficial as being together and doing that."

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