With hopes of solving a decade-long problem, the Lions drafted three cornerbacks in 2012, but as the 2013 season approaches, cornerback remains one of the team's most unsettled positions.

Second-year players Bill Bentley, Chris Greenwood and Jonte Green will battle for playing time this season, but their 2012 play — or lack thereof — leaves many questions about how the positional battle will shape out.

On the heels of signing a five-year, $25-million contract, Chris Houston has the left cornerback spot secured, but the right cornerback and nickel slots will be among the most hotly contested positions during training camp.

The three second-year players will be in the mix, but 2013 second-round pick Darius Slay and veteran Ron Bartell will have a chance to compete, too.

"Basically you're looking for growth from last year," Houston said of the second-year cornerbacks. "You want to see if they understand the game a little better and compete."

Bentley, a third-round pick, likely has the best chance to be the No. 2 cornerback because he's already held the position, making three starts before going on injured reserve with a shoulder injury. To climb back up the depth chart, Bentley said he has to start from scratch after a "devastating" experience watching from the sidelines in 2012.

"Every day you've got to put something different together," he said. "I'm starting from scratch. I wasn't really helping the team the way I wanted to help last year, but everything doesn't go as you plan. Hopefully things can get better this year."

Bentley spent much of the offseason rehabbing his shoulder and said the injury gave him a different perspective on football.

"Coming off an injury, not being there and then when you get a chance to come back, you just take a different approach to the game," he said. "You want to be out there every day. You don't want to waste no reps, and you just want to take everything serious, from the classroom to the field

"(Rehab) was tough at first, but I knew I had to get back right. That was my mind-set, so I had to attack it more than it was attacking me."

Greenwood's rookie season also was marred by injury, and an abdominal injury kept him out the entire year. The fifth-round pick from Albion spent the 2012 season learning the defense and picking coaches' brains, but his lack of reps creates a hurdle to playing time in 2013.