Our preview of the NFL's soon-to-begin free agency period has focused largely on what the Tampa Bay Buccaneers could potentially take from the list of available players. When it comes to running backs, however, we have to start with what the Buccaneers could be giving to the marketplace.

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The biggest and most important question regarding the 10 players from Tampa Bay's 2015 roster who are due to become unrestricted free agents (UFAs) on March 9 is what will happen with running back Doug Martin. Martin is set to hit the market after a superb season in which he ranked second in the league in rushing yards and averaged a robust 4.9 yards per tote. Both sides have expressed interest in Martin's return to the Buccaneers, but nothing is guaranteed unless the team chooses to employ it's franchise tag. The deadline to do so is on Tuesday.

What happens with Martin will obviously affect how significant the team's need is for a running back during the 2016 offseason. RB Charles Sims also had an outstanding season in his second year in the league, with 1,090 yards from scrimmage and his own 4.9-yard rushing average, and could be ready to take on a larger role. Versatile and hard-working reserve Mike James is under contract, as well, though Bobby Rainey, the team's primary return man last year, is on that same list of pending UFAs.

Increasingly, running back has been a position at which teams can find useful help all throughout the draft, so the Bucs could choose to address any depth chart shortcoming in that manner. However, there is some opportunity in this year's field of free agent backs, so the team might not need to wait to late April to make such a move. If there is no new deal for Martin before March 9, Tampa Bay would be one of 32 teams with a chance at signing him, albeit one with a greater connection to the player than most.

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So, after previously checking out what the market has to offer at defensive end, wide receiver, guards/centers and linebacker, we now turn our attention to…

Running Backs

We're lumping the fullbacks in with the tailbacks here. Generally, the fullback position isn't a high priority in free agency, but it's worth a brief discussion here because there are some interesting names potentially hitting the market. In addition, the Bucs' incumbent starter at the position, Jorvorskie Lane, is recovering from a significant leg injury suffered in the 2015 season finale.

But first, the primary ballcarriers. Including Martin, this year's class of potential free agents includes two of the top five rushers in 2015; the other is the Jets' Chris Ivory, who finished fifth with 1,070 yards. Another player who ranked in the top 10 in rushing yards per game played, Arizona's Chris Johnson, could hit the market as well.

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Martin and Sims proved to be perfectly complementary backs in 2015, and what the former could bring to Dirk Koetter's attack in 2016 is well-known and attractive. Could Ivory or Johnson offer the same sort of complement to Sims? Ivory is three years younger than Johnson and has logged about 1,200 fewer carries in his career, so he will probably be seen as a sounder free agency investment by most teams. Still, Johnson showed some of his old CJ2K big-play ability last year in Arizona before getting hurt and was a good pairing with David Johnson in the Cardinals backfield. Few teams want to invest long-term in older tailbacks in today's NFL, but he could help on a shorter deal. Ivory finally got a chance to log over 200 carries in a season last fall in his sixth year in the league and he used it to crack 1,000 yards and average 4.3 yards per tote.

Two other free agent backs were established starters with their respective teams in recent years. Again, we have a pairing in which one player is significantly farther along in his career with another that might still be entering his prime. The former is long-time Chicago Bear Matt Forte, who turned 30 last December and has logged 2,035 carries and another 487 receptions in his career. The latter is Miami's Lamar Miller, who is 24 and has 638 career carries and 117 receptions.

Forte is obviously the more accomplished of the two; in fact, he's been one of the NFL's most productive for the most part of the last decade. As his reception totals indicate, he has always been a three-down dual threat, with a total of 12,718 yards from scrimmage and 64 touchdowns. His yards from scrimmage declined from an average of nearly 1,900 per year in 2013-14 to close to 1,300 last year, but he still averaged 4.1 yards per carry. Chicago is ready to move on with Jeremy Langford in the backfield but Forte can surely help another team for the next couple of years.

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Miller is fast – he ran a 4.40 40-yard dash at the 2012 Scouting Combine – and his big-play ability shows in his four seasons of per-carry averages in the NFL: 4.9, 4.0, 5.1 and 4.5. It is also fair to say that Miller hasn't played behind the NFL's best offensive lines during his four years with the Dolphins; Football Outsiders ranks Miami's run-blocking work 21st or worse in three of those four seasons. Miller is the type of free agent that teams can sign with the hope that his production moving forward will be greater than what they've seen so far. That's a lot less likely with a signing of Johnson or Forte, or perhaps even Ivory.

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Both* of the primary running backs for the defending-champion Denver Broncos are pending free agents, but C.J. Anderson, unlike Ronnie Hillman, is going to be a restricted free agent. That makes Hillman much more likely to hit the market, as does the fact that Denver has some other very pressing issues (Von Miller, Brock Osweiler) to take care of in free agency. Like Miller, Hillman is just 24 and he's averaged 4.1 yards per carry in his career while showing some talent as a pass-catcher.

If the Jets manage to hold on to Ivory, they could still lose his backfield mate, Bilal Powell. In five years in New York, Powell has never had more than 176 carries or 697 rushing yards in a season, but he caught 47 passes last year and 36 in 2013. Given that, in a Buccaneer backfield scenario that does not include Martin, the team's starter is also a very talented pass-catcher, Powell might be a better fit for a team with a different sort of starting tailback.READ: FREE AGENCY PREVIEW - LINEBACKERSAlfred Morris, who battled Martin for the title of best rookie back in 2012, is hitting the market after starting every game over his first four seasons. However, Morris is three years older than Miller and Hillman and he has seen his rushing yards decline every year. Last fall, he ceded a lot of carries to rookie Matt Jones, averaged just 3.7 yards per tote and scored only one touchdown. He's also never been a receiving threat. LeGarrette Blount, the one-time Buccaneer, probably isn't going to be a long-term starter anymore, but he still averaged 4.3 yards on 165 carries and scored six touchdowns last year in New England. He has averaged over 4.5 yards per carry over the past three seasons, so he could probably add something to a backfield looking for a big and physical ballcarrier.

One final interesting option is Green Bay's James Starks, who has always been a complementary piece in a half-dozen years with the Packers. Starks is 30, but he's logged only 555 carries in his career. A career-high 148 of those came last year, and while he didn't prove to be a consistent threat he did have a handful of big games. Starks also caught 43 passes, three of them for touchdowns.

As for the fullbacks, the list starts with one who was voted into the Pro Bowl this past year and another one who eventually played in that game. Carolina's Mike Tolbert was busy with Super Bowl preparations, so he didn't make the trip to Hawaii, but Green Bay's John Kuhn did in order to replace Oakland's Marcel Reece. Kuhn has been named to three of the last four Pro Bowl rosters.

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Tolbert occasionally got an underneath handoff for the Packers in short-yardage but Tolbert actually has a pretty long track record as a ballcarrier in addition to his lead-blocking. Tolbert's career numbers including 595 carries for 2,288 yards and 33 touchdowns, so he would likely fit into the rushing mix with whatever team he plays for in 2016. Obviously, he may be motivated to return to the Panthers to try to make another run at a title.

The 33-year-old Kuhn might wish to stay home and make it a solid decade in Green Bay, too, since the fullback position has more limited earning potential than some others on the market. Teams looking for other options may check out Washington's Darrel Young or the Cowboys' Tyler Clutts.

Bucs' Overall Interest Level at the Position: Moderate (Potentially)

Again, the last week before the start of free agency will likely determine how much attention the Buccaneers pay to the running back position once the market opens. If their own top-notch free agent is still on that list of available players, that would significantly increase the team's need in the offensive backfield. If Doug Martin is back in a Buccaneer uniform, the tandem of him and Charles Sims would seemingly make that position a very low priority for the rest of the offseason.