ALLEN PARK -- Ask Lions running backs coach David Walker about his new toys in the backfield and he'll point out another you might have missed.

"Probably the biggest piece was Frank with the first pick," Walker said of Ragnow, the Arkansas center Detroit drafted 20th overall. "Let's not understate that."

Yes, the Lions have added to the backfield a year after they chose to ignored it and got burned by a last-place finish in rushing. They did so in different ways, with a proven free-agent power back in LeGarrette Blount and a do-it-all rookie they traded up for in the second round in Auburn's Kerryon Johnson.

But even the biggest believer in these backs or Theo Riddick or Ameer Abdullah will admit that much of their success begins before they touch the ball. Despite the numerous investments Detroit had already made in its offensive line, it went to that well in some significant ways again this offseason, starting with a couple assets the Lions haven't had for a few years now: an experienced offensive line coach and an assistant for him to work with.

Jeff Davidson comes to the Lions with eight years of experience in Cleveland, Minnesota, San Diego and Denver performing the job he'll be asked to do now of designing blocking schemes as offensive line coach. He was also an offensive coordinator for five years between Cleveland and Carolina, playing a different but impactful role of shaping the front wall.

As a former starting guard of the Broncos who chose to hire an assistant in Hank Fraley, Davidson comes to the Lions as the antithesis to Ron Prince in some ways. Prince never played the position, had never been a head offensive line coach before and did not use an assistant in his three years with the Lions before Detroit sent him packing the morning after the season finale.

"Obviously, Jeff's been around for a long time. He's a former player himself. He knows what it's like sitting in those chairs," right guard TJ Lang said.

In 13 years as a coordinator or offensive line coach, Davidson has had 67 rushers hit 100 yards in a game. The Lions have done that 13 times in those 13 years with none coming in the past four seasons.

It's easy to tie a chunk of Davidson's success to the backs he's gotten to work with, from Adrian Peterson to Melvin Gordon to Jonathan Stewart. But Detroit is hoping its backs can offer something as well. It's only going to happen if the holes they see are wider and available on a consistent basis.

"The run game in general is something that we have to make sure we're taking on our shoulders, and we as an entire unit say that in order to get another one called, we have to earn it," Davidson said.

The Lions saw the reverse of that play out last season. They converted just 7 of 14 times when they had a third or fourth down and just one yard to go. By late in the season, they were passing often on 3rd and 1 just because it was too difficult to run if the defense knew what was coming.

It led to an unbalanced team, as the Lions finished sixth in passing yards and 32nd in rushing en route to a 9-7 season. It keyed the focus of their offseason, from bringing in a powerful interior lineman in Ragnow to a 250-pound veteran back in Blount to a physical runner from the Southeastern Conference in Johnson. Even depth moves like taking Oregon tackle Tyrell Crosby in the fifth round and San Diego State fullback Nick Bawden in the seventh seemed to hold more of a physical purpose in mind, and general manager Bob Quinn admitted as much when he said he was bothered by the lack of toughness last year's team had in short-yardage situations.

Davidson said his line will run a variety of schemes between power and zone, much like most of the NFL. Regardless of which one they draw up on a given play, the blocking has to set the tone to give the offense some level of faith that it hasn't had in recent years.