Whom the Bucs have
Doug Martin (5-9, 223): Re-signed to a $35.7 million, five-year deal after finishing second in the NFL in rushing. How does he improve in 2016? Score more touchdowns — of the last 25 1,400-yard rushing seasons in the league, only four came with fewer rushing TDs than Martin's six last year.
Charles Sims (6-0, 211): Strong complement to Martin last year, topping 500 yards in rushing and receiving. Can team find a package to use them both (and their pass-catching skills) in same backfield?
Mike James (5-10, 223): Practice squad in 2015, 37 yards in 2014. Even with Bobby Rainey gone to Giants, needs to step up to make it as No. 3 RB in 2016.
Depth: There is none. The Bucs have only three tailbacks on the roster — what they dressed each week last season — and no fullback. Whether it's a late-round pick or postdraft signing, expect the team to add a tailback to challenge James for the No. 3 job, and a fullback — should the team decide to carry one in 2016.
Top five draft prospects
Ezekiel Elliott, Ohio State (6-0, 225): Go back to the end of 2014: 220, 230 and 246 yards in three games closing out a national title for Buckeyes. Big-play potential, could go as high as No. 4 to Cowboys. Would Miami trade up if he falls past Dallas?
Derrick Henry, Alabama (6-3, 247): A workhorse — 36 carries in national championship win, 46 and 44 carries in other wins. His size is rare, even in the NFL. Does he sneak into the end of first round to a team such as Seattle?
Kenneth Dixon, Louisiana Tech (5-10, 215): Less of a wow factor than top two but consistent production: 72 career rushing TDs, with 64 catches in 2014-15.
Alex Collins, Arkansas (5-10, 217): Three straight 1,000-yard seasons, with 20 touchdowns as a senior. Watch out for teammate Jonathan Williams.
C.J. Prosise, Notre Dame (6-0, 220): Converted receiver played just one season at running back and turned heads with 91-yard touchdown. Third round?
Under the radar
Marshaun Coprich, Illinois State (5-8, 207): Drug-related arrest is a red flag but blazing 4.47 speed — rushed for 1,967 yards and 23 TDs in 2015. Third-day steal.
Bucs did well to keep Doug Martin after a stellar 2015 season, so there's continuity at a key part in their offense. They let No. 3 RB Bobby Rainey go in free agency and didn't re-sign Jorvorskie Lane, so there will be new depth behind Martin and Charles Sims.
Could the Bucs take a late-round back to take Rainey's place, perhaps doubling up to help on returns as well? The No. 3 RB job is as wide open as any spot on the 53, so even an undrafted rookie could make the team with a strong summer.
Greg Auman, Times staff writer