Training camp preview: Running back

Breaking down the New York Jets' roster, unit by unit, in preparation for training camp, July 23:

Position: Running back

Projected starters: Chris Johnson, Tommy Bohanon (FB).

Projected reserves: Chris Ivory, Bilal Powell.

Notables on the bubble: Alex Green, Daryl Richardson.

Player to watch: Johnson. Five years removed from his 2,000-yard season with the Tennessee Titans, the once-great running back starts over with the Jets, attempting to prove he's still CJ2K. His surgically repaired knee, which sidelined him for the spring, will be a hot topic throughout camp. The last thing the Jets will want to do is tax Johnson, so look for a modified practice schedule -- a "pitch count," as Rex Ryan likes to call it. It doesn't matter how many rushing yards he accumulates in the preseason; the objective is to make sure he's in peak condition for the Sept. 7 opener.

Top storyline: Chances are the Jets will take a backfield-by-committee approach, which underscores the importance of defining roles. Who starts? Who's the third-down back, Powell or Johnson? Is Ivory the short-yardage back? Who gets the rock in the four-minute offense? It will be a balancing act for the coaches as they attempt to navigate four weeks of camp and three preseason games. (We're not counting the last game, which is useless.) There aren't as many practice reps as the not-so-old days, when teams had two practices per day. Every rep counts.

Training camp will be a success if ...: Every back is healthy and fresh for the start of the season. Injuries can change the landscape, as we saw last summer. Because of a spate of injuries, Powell was overworked in training camp, which is probably the reason he ran out of gas during the season. It will be easy to fall into that trap again, considering Johnson's limited schedule and Ivory's penchant for nagging injuries. Remember, he finished minicamp with a sore ankle; let's see if there are any residual effects.

Wild card: Richardson. He was acquired on waivers in May, but missed the rest of the offseason as he recovered from a turf-toe injury that ruined his 2013 season with the St. Louis Rams. He's a change-of-pace back who showed promise as a rookie in 2012, averaging 4.8 yards per carry. The Jets are eager to get him on the field to see if he has the same explosiveness he showed in '12. He'll need to show his old form to make the roster.

By the numbers: Weird stat on Johnson -- his per-carry average last season for the Titans was slightly better with eight defenders in the box (3.83) than seven in the box (3.79), according to ESPN Stats & Information. Only Adrian Peterson and Frank Gore ran against more eight-man fronts than Johnson, who rushed 48 times for 184 yards and one touchdown. It shows that opponents still respected him despite a down year.