Chris Johnson isn’t the only running back having trouble understanding why the Titans signed free agent Shonn Greene. Javon Ringer, who spent the past four seasons as Johnson’s backup and is a free agent, is scratching his head as well. “I am happy for Shonn because I know him from playing in the Big Ten, and he’s a good guy. He’s a good running back,” Ringer said. “But when they got him I said, ‘Dang, they had some guys who never got a chance to play, so why are they adding someone like that?’ “All this talk about them needing another running back to help C.J., it kind of made me upset. I’m like, ‘Man, they had some good running backs behind C.J., and they just never really got a chance.’ And because we were not able to play, it made it look like C.J. didn’t have any help. C.J. had some help, but they never used it. It’s frustrating.” The Titans signed Greene to a three-year, $10 million contract, and coach Mike Munchak said the former Jet would be more than a short-yardage and goal-line back. Johnson expressed concern about the move, saying he wasn’t a “big fan of the two-back system. … I don’t mind a guy getting a carry or two. But if I am the main guy and it is supposed to be my team … it shouldn’t be an issue.” Ringer, a fifth-round pick of the Titans in 2009, had 120 carries for 486 yards and three touchdowns in four seasons. Last season he played in only two games because of a knee injury. He had arthroscopic surgery in January and won’t start running until next month. “I feel like I am a good running back. I just wasn’t able to give it a real good shot in Tennessee, but I do feel like the opportunities I got I was able to produce,” Ringer said. “I was backing up one of the NFL’s best running backs. Now I just want a shot, a fair opportunity, and hopefully I can get that somewhere else.” Ringer suffered a number of injuries with the Titans, but when healthy he rarely touched the ball. In 2010 he played in every game but got only 51 carries. In 2011 he played in 12 games with 59 carries.