IRVING, Texas -- The Dallas Cowboys agreed to terms Saturday night with Memphis guard Ronald Leary as an undrafted free agent.

Cowboys offensive line coach Bill Callahan attended a private workout for Leary in late March and came away impressed. The key for Leary is his knee. Cowboys owner/general manager Jerry Jones said the team gambled by not selecting an offensive lineman in the three-day NFL draft because they figured Leary would not get drafted. Leary's knee issues scared off several teams.

After extensive research, the Cowboys determined Leary has a chronic knee problem that will allow him to play now but might limit his long-term future.

"The issue for him is how long [he can play], it's not now. It's how long he can play," Jones said Saturday night. "That's why he fell the way he fell. We had our coach think he might be the readiest of any [drafted] offensive linemen."

In free agency, the Cowboys signed guards Nate Livings and Mackenzy Bernadeau to contracts worth $30 million. As the draft approached, the Cowboys were linked to Stanford guard David DeCastro, but instead moved up from the No. 14th overall spot to No. 6 and selected LSU cornerback Morris Claiborne.

The Cowboys picked defensive players with their first four picks, the first time that's happened since 1982.

And while the Cowboys still wanted to draft an offensive linemen at some point during the draft, team officials saw getting Leary as a positive.

"Here's a guy who gives us a chance to [play him] now," Jones said. "It helped me because there's risk here, and it helped me talk about [playing] now as opposed to development. He can get in here and play now."

Leary, at 6-foot-3, 325 pounds, was a second-team All Conference USA selection in 2011.

The Cowboys also agreed to terms to an undrafted free agent contract with North Texas running back Lance Dunbar.