Will Ameer Abdullah or Theo Riddick receive more carries for Lions in 2017?

When he's been healthy, RB Ameer Abdullah has been very productive. Zach Bolinger/Icon Sportswire

The Lions needed to improve their running game. It was an obvious hole for the franchise, one that has been an issue for Detroit almost every season since Barry Sanders’ retirement in 1999.

In the franchise’s latest attempt to fix this, Detroit upgraded its offensive line in the offseason with right guard T.J. Lang and right tackle Rick Wagner. The Lions added one of the better blocking tight ends in the league, Darren Fells.

But the actual running backs? So far, not much has changed from last season. And that leads to today’s Lions Mailbag question. To ask a question for a future Mailbag, email me at michael.rothstein@espn.com or ask on Twitter @mikerothstein.

Running back is one of the more intriguing questions for the Lions after free agency and the draft were sorted out. The Lions had one of the worst rushing offenses in the league, but were also without a healthy Ameer Abdullah and Theo Riddick for long stretches of last season.

Abdullah is healthy after foot surgery last season. The Lions hope Riddick gets back to health after two wrist surgeries this offseason. Between the two of them, the Lions believe they have a strong core in the backfield.

And as long as Abdullah is healthy, he’ll get a good chunk of the carries this year, certainly more than Riddick, who works best as a change-of-pace, two-minute, passing-down back. That’s where he’s thrived. That’s why the Lions paid him good money before last season to stay with the franchise.

But Abdullah is the main back and when he’s been on the field, his production has been good. As a rookie, he averaged 4.17 yards per carry. Last season, before the injury, he was averaging 5.61 yards per attempt.

If he’s able to do that for a full year, the Lions would gladly take that -- and it would probably improve the franchise’s running game immensely.

And when coach Jim Caldwell was asked about the team not taking a running back during the draft -- the Lions signed 6-foot, 220-pound Tion Green as an undrafted free agent -- he defended the guys he has on his roster now.

“I believe Ameer Abdullah, when he’s healthy and rolling, he’s awfully good. All you have to do is just take a look at the numbers. Don’t listen to me. Look at the numbers and see when he’s on the field for you what he does. When Theo is out there healthy for us, I mean everybody knows what he can do. Those guys create a punch and I don’t think anybody in this room has any questions whether or not Zach Zenner can run the ball,” Caldwell said. “We’ve got a young guy in Dwayne Washington. Nobody really knows how good he can be, but he has talent. He has ability. We like what we see in that particular area and he’s developing and then we’ve got Mike James as well. So we have a pretty good group of guys and, obviously, Tion [Green] is a part of that group in free agency.

“We’ll see what happens, but I think overall, we’ve got some pretty good depth there. Now, do we look to improve anytime that we can? You better believe it. Anytime we can, we look and we see if it fits us and if it does we’ll make that decision. If not, we’ll move on.”

Among the guys the Lions could look at are former Vikings running back Matt Asiata, who was expected to participate in Lions rookie minicamp last weekend, and veteran LeGarrette Blount. Caldwell declined to answer any questions about the team’s interest in Blount when he spoke to the media Friday.