IRVING, Texas – The Dallas Cowboys signed probable starters at both guard spots and fullback in March, but their most important offensive addition won’t put on a pair of shoulder pads.

That would be offensive coordinator/offensive line coach Bill Callahan.

How key is Callahan? The presence and experience of an assistant who has been a head coach and playcaller for a Super Bowl team should expedite the process of Jason Garrett reaching his potential as a head coach.

It’s no secret that Garrett struggled with some game-management situations in his first full season as a head coach. It’s also a fact that Garrett’s best statistical season as a playcaller occurred in the one year that he had running game guru Tony Sparano help prepare the game plans.

Callahan, a head coach for two seasons with the Oakland Raiders and four seasons at Nebraska, should be a tremendous asset to Garrett in both of those facets of the game.

“Certainly his experience as a coordinator and a head coach will help us,” Garrett said. “He and I have talked about that. He’s someone that I can lean on.”

Garrett will continue to call plays, but Callahan will make recommendations on runs or pass protections during games. Callahan also said he still thinks like a head coach during games and won’t hesitate to make suggestions to Garrett on situations that arise.

“Whatever those situations are, I’ve got enough experience in my background to assist where he needs help,” Callahan said. “I will say this, though: A lot of that stuff is done during the game plan week. That’s where I see that I can really contribute and help this staff is during the course of the week. Then if you’re well prepared, I think it just unfolds on game days. You’re ready to make those crucial calls.”

Garrett’s willingness to take input is a critical element to his relationship with Callahan working. The chain of command is clear, but Garrett isn’t too proud or stubborn to realize that he’s a young head coach who can benefit from Callahan’s experience.

“He’s really open,” Callahan said. “That’s the great thing about Jason. He’s a great listener. He’s wide open to thoughts and ideas, anything you have to offer, suggestions, whatever it may be. That’s been great.

“I’m sure it will be that way on game day, but I do respect his ability to call plays. He’s had a great knack for it. He’s had offenses that have been close to being on top of the league. I think the work relationship has been terrific, and I only see it getting stronger as we move along.”