One free-agent defection that sent the Chicago Bears scrambling for replacement help was Pro Bowl punt gunner Corey Graham, who is now with the Ravens.

Special teams coordinator Dave Toub has been auditioning players at camp for the spot, and one is intriguing -- but possibly a gamble. D.J. Moore, the team's nickel back for the past two seasons, has made strides there.

"He is the quickest player we have," Toub said.

Moore, however, is only 5-foot-9, 180 pounds. Graham is 6-foot, 196. Size and speed are ideal at gunner, where players are outmuscling and outrunning each other.

"Corey Graham didn't have the greatest quickness or speed, but his effort was second to none," Toub said. "That's what made him so good. We're trying to find that next Corey Graham."

At what cost? Moore helped solidify the Bears' third-down pass defense when he became the nickel back. With Moore in the nickel package, the Bears tied for fourth in third-down percentage in 2010 while making the NFC title game, and they tied for sixth (31.5) last year.

Risking Moore with that type of extra duty could hurt a team that lost its backup nickel back -- Graham.

Wide receiver Devin Moore and rookie corners Isaiah Frey and Greg McCoy also are being considered.

Follow Bears reporter Gene Chamberlain on Twitter: @CBSportsNFLCHI