The biggest question regarding the Oakland Raiders signing free-agent running back Maurice Jones-Drew to a three-year contract on Friday is this: How exactly do they plan to use him in their retooled offense? As the bellcow? In tandem? As insurance?

Jones-Drew said he was told by the Raiders he was coming in to compete.

"We have different running abilities," he said in a conference call Friday. "But the competition is what's going to make us better. We'll push each other."

He joins a crowded if somewhat unsettled backfield.

Since being the No. 4 overall draft pick in 2008, Darren McFadden has been the Raiders' starter ... when healthy. And Oakland re-signed him to an incentive-laden deal to do just that in 2014, even though he has missed 19 of the Raiders' previous 41 games and has never played more than 13 games in a season.

The Raiders are also high on Latavius Murray, who missed all of last season with an ankle injury after being drafted in the sixth round. Plus, they signed Canadian Football League Grey Cup MVP Kory Sheets, and the Raiders still have Jeremy Stewart on the roster.

Or, as Murray tweeted:

one dangerous backfield @dmcfadden20 @Sheets24K @J_Stew32 @Jones_Drew32 #RaiderNation @RAIDERS

— Latavius Murray (@LataviusM) March 28, 2014

Jones-Drew, a diminutive three-time Pro Bowler who has a lot of mileage on his powerful legs, has had health issues himself of late. It just so happens that in the past two seasons, those injuries occurred in Oakland.

In 2012, after holding out in the preseason, the 5-foot-8, 205-pound Jones-Drew broke his left foot on the Jaguars' second play from scrimmage against the Raiders in Week 7 and did not play another down all season. He underwent what he termed "major" surgery that offseason.

Last season, Jones-Drew sprained his left ankle on a touchdown-saving flying tackle by Charles Woodson in the first quarter of the Week 2 game.

"It was a hell of a tackle," Jones-Drew said, "there's nothing I can say."

Jones-Drew, 29, missed the rest of that game but played the rest of the season, rushing for 803 yards while averaging a career-low 3.4 yards per carry. His previous low was his 4.2 in 2008.

"I feel like I have a ton left in the tank," he said, and maybe splitting time with McFadden would keep both off the injury report. Or perhaps it limits their efficiency and productivity in smaller-than-usual roles.

Whatever the case may be, Jones-Drew grew up in the East Bay a fan of the Raiders, prepped at high school powerhouse De La Salle and has lived in the Bay Area every offseason since Jacksonville selected him in the second round of the 2006 draft out of UCLA. Playing home games in front of his grandmother now, he said, would be a bonus.

Jones-Drew said the other teams that reached out to him wanted him to join them in a mentor role, or as a backup.

"But the Raiders," he said, "gave me an opportunity to compete.

"It just feels like home."