Jim Caldwell expects Ameer Abdullah to have a big season for the Detroit Lions in 2016.

Abdullah received a lot of hype in the preseason but couldn't maintain a consistent level of production in the regular season.

"If there's anybody who is going to improve, he's going to improve," Caldwell said in Boca Raton this week at the NFL Annual Meeting, via MLive.com.

He added: "I think that he was able to (get a lot better) during the course of the year. He had some peaks and valleys, but obviously, I think he's going to be OK."

Abdullah was a second round pick by the Lions in 2015.

Matthew Stafford could see how the NFL was wearing on Calvin Johnson.

"Not to say that I expected it, but I wasn't shocked," Stafford said, via the Detroit Free Press. "I've known Calvin for seven years and know the effort and the attitude that he plays with, and it takes a toll on people. And he was catching quite a few passes and getting hit quite a bunch, and so it takes a toll. And he's a guy that from an offensive standpoint was touching the ball or carrying the ball just as much as anybody. So I knew the NFL was kind of wearing on him and I just told him, when he told me he was done, I just told him, 'I'm happy for you if you're happy.' And that's what you want. He's a guy that gave everything to the game and you want him to be able to walk out on his own terms and feel like he did the right thing."

Stafford admitted duplicating Johnson's explosiveness and production would be difficult.

"It'll look different, obviously," Stafford said. "He was a player that drew a bunch of attention, not only in the red zone but all over the field. He was a guy that led that receiver group, showed those guys what it was like to work and what it was like to try and dominate a game, take over a game. We have obviously replaced with some pieces. No one player is going to replace a guy like that, but I'm confident in our coaches and our players that we have on our team, we're going to be fine."

The Detroit Lions have agreed to sign Marvin Jones on a five-year, $40 million deal. Jones will receive $17 million in fully guaranteed money.

The agreement between Jones and the Lions comes less than 24 hours after Calvin Johnson announced he was retiring from the NFL after nine seasons in the league.

Jones emerged with the Cincinnati Bengals as the perfect complement to A.J. Green.

Although he can easily sprint past a corner on a deep go route, Jones' best attribute has long been his ability to catch passes in traffic, particularly on short fields from inside the 20.

Calvin Johnson has retired from the NFL after nine seasons.

Johnson holds 15 NFL records, including the most receiving yards in a season with 1,964 in 2012.

The Lions announced Tuesday that Johnson has filed his retirement papers with the NFL in advance of the start of the new league year, which starts Wednesday at 4 p.m. ET.

Johnson announced on Jan. 6 he was evaluating his options for the future and now he's made that decision. 

Johnson had said consistently over the past few months he wanted to play his entire career in Detroit and wanted to win with the Lions.