The first wave of free agency is essentially over. Signings will continue sporadically up to and even beyond the draft but nearly all of the most coveted players have already found new homes. Teams that hoped to use the free agent market to make significant changes to their depth charts have done so by now.

Count the Tampa Bay Buccaneers among those teams. Other than re-signing their own star running back, Doug Martin, the Buccaneers mostly stayed away from the big-ticket signings. Instead, General Manager Jason Licht sought value and proven performers at areas of need, adding up to a half-dozen potential starters to a very promising young core of talent.

READ: BUCCANEERS RE-SIGN DOUG MARTIN

Licht and Head Coach Dirk Koetter aren't done reshaping the roster, largely because the all-important draft still looms about a month away. Still, the Bucs' roster definitely has a different look after that initial wave of free agency. As we close out March and close in on the draft, let's see how the depth chart is shaping up after the additions of the last few weeks.

Today, offense. Tomorrow, defense and special teams.

Quarterback

The Bucs were never expected to shop in the QB aisle in free agency. As Koetter put it at last week's Annual Meeting in Boca Raton, Tampa Bay is blessed with more depth at that spot than most teams in the NFL.

In fact, the main question surrounding the Bucs' stable of passers is whether or not they will subtract from the position in the coming weeks. As both Licht and Koetter have acknowledged, other teams have expressed interest in Mike Glennon, the fourth-year passer who gives the Buccaneers an experienced backup to second-year starter Jameis Winston. Licht and Koetter love having Glennon on their roster but have to acknowledge that he has potential value as a trade target, as well.

READ:**QUARTERBACK DEPTH GIVES BUCS OPTIONS**

The Bucs also have third-year quarterback Ryan Griffin in the fold and they believe he could be a viable backup to Winston, too, though he lacks regular-season playing experience. If Glennon ends up elsewhere, then the Buccaneers might have some belated interest in the remaining veteran quarterbacks on the market.

Running Back

Re-signing Doug Martin was the first order of business, and doing so on the first day of free agency meant the team didn't have to chase Lamar Miller or Chris Ivory or any of the other viable starting backs who hit the market. Tampa Bay believes it has one of the NFL's best one-two punches in the backfield with Martin and third-year man Charles Sims, and solid backup Mike James remains on the roster, as well.

So, again, this is a position that became a non-factor for the Buccaneers in free agency as soon as Martin inked his new deal. If the team desires a little more depth at that position, or at least training camp competition, it can almost surely find it in the draft or in the post-draft signing of rookie free agents.

The most significant change to the running back position via free agency is the apparent departure of Bobby Rainey, who currently remains unsigned. Rainey's role on offense has diminished greatly the past two years but he did spend much of 2015 as the team's primary kick returner. It looks like the team will be searching for different options there in 2016.

READ:JOEL GLAZER, YOUNG CORE A SOURCE OF OPTIMISM

That said, the Bucs might still address the running back position in free agency because, as of now, there is a complete void at fullback on the depth chart. Koetter acknowledged that roster shortcoming at the league meeting but also mentioned how difficult it is to find a solution at that position. Though the fullback position has been somewhat marginalized in the NFL in recent years, Koetter does want to have one in his offense.

Wide Receiver

While there was no reason to expect the Buccaneers to go after quarterbacks or running backs (other than Martin) in free agency, one could have made the argument that an addition at wideout made sense. The Bucs may have kicked some tires, but they didn't sign (or haven't yet signed) a receiver, and that in itself tells us a bit about how the team feels about its corps of pass-catchers.

Most notably, Koetter thinks the Buccaneers are set at the two starting positions with the returning duo of Vincent Jackson and Mike Evans. A pair of leg injuries kept Jackson from extending his streak of 1,000-yard seasons from four to five but he still averaged 16.5 yards per catch when healthy. Evans actually improved upon his rookie-season yardage total last year, from 1,051 to 1,206, but scored nine fewer times and had occasional problems with dropped passes.

"I feel fine about our receiving corps, obviously at the top with Vincent and Mike," said Koetter. "I'm not a believer that Vincent Jackson is anywhere close to being done. I think both of his injuries were extremely freakish last year. He happened to take a helmet right on the knee on both instances. Vincent is a fast healer. I think Mike's going to have a rebound year, if we can call 1,200 yards a bad season."

Koetter also noted that Louis Murphy and Kenny Bell are returning from injured reserve, as well, and they'll be competing for playing time with Adam Humphries, Evan Spencer and Russell Shepard.

READ: MARTIN EXPECTS GREAT THINGS FROM THE OFFENSE

"And I'm really excited for the competition we have with the four young guys. Between Adam, DD, Kenny Bell coming back and Evan Spencer, I'm really excited for those four. Then you've got the two vets in Louis Murphy and [Russell] Shepard. So I think we've got great competition…and that's pre-draft talk. I don't think at wide receiver we're in bad shape at all."

Koetter isn't alone in thinking the Bucs are in good shape at the top of the depth chart with Jackson and Evans. It's not obvious, however, who would line up as the third and fourth receivers from that group above. That understandably created speculation that the team would be looking for an outside option, particularly with an emphasis on speed to work between the gigantic outside pair of Jackson and Evans. There wasn't necessarily an opportunity to add such a player in March, however.

Well everybody would like to add a speed receiver," said Koetter. "But when you talk about a speed receiver, those guys have got to be able to play. There were some guys that we looked at ... a speed receiver still has to be able to show up on third down, has to be able to play in the red zone. A speed receiver can't just get behind the defense twice a game and maybe you hit it, maybe you don't. Yeah, everybody's looking for a speed receiver that can play."

Tight End

The Buccaneers' tight end depth chart, which by the end of the 2015 regular season ran five deep, returns intact to start the 2016 offseason. For that reason, the team wasn't particularly motivated to wade into a mostly uninspiring pool of free agents at that position.

The tight end ranks swelled to five in December when first-year player Tevin Westbrook got a late promotion. The three players who were seeing the most playing time as the season neared its end, however, were Austin Seferian-Jenkins, Luke Stocker and Cameron Brate. Brandon Myers represents a proven do-it-all option at tight end but was a healthy scratch for the last five contests after Seferian-Jenkins returned from a long injury absence.

Seferian-Jenkins' only real question mark is health, as various injuries have caused him to miss 16 of a possible 32 games since the Bucs drafted him high in the second round in 2014. Koetter called Seferian-Jenkins "unlucky" last week at the Annual Meeting and said the young player has "huge ability." He is clearly at the top of the Bucs' depth chart when healthy because he is that rare tight end option who can provide plus production as both a blocker and a pass-catcher. Meanwhile Stocker has carved out a nice career as a very good blocking tight end and Brate, a former undrafted free agent from Harvard, has shown he can make big plays in the passing game while he works to improve his blocking.

READ: BUCCANEERS ADD FLEXIBILTY TO DRAFT PLANS

Nothing happened in free agency to shake up the Bucs' depth chart at tight end, and that will probably remain true straight to training camp.

Offensive LinePro Bowl guard Logan Mankins retired right before the start of free agency in early March. This did not come as a particular surprise, and the Buccaneers were clearly ready with a contingency plan, quickly signing unrestricted free agent J.R. Sweezy from the Seahawks. That's a significant change to the depth chart – Sweezy is expected to step right in at the left guard spot vacated by Mankins.

Though that's a switch from right guard, which Sweezy played throughout his four years in Seattle, that's an adjustment he should be able to make. After all, Sweezy already converted from defensive line, which he played at North Carolina State, to the other side of the ball in the pros.

The addition of Sweezy meant that the Bucs didn't have to move one of their potential starters at center – Joe Hawley and Evan Smith – over to guard. It also meant they could bide their time with promising young lineman Kevin Pamphile and see what position needs his help the most. Koetter said last week that Hawley and Smith would start the offseason in a competition for that starting center spot, where both played and received good reviews last year. Last year's two rookie starters, left tackle Donovan Smith and right guard Ali Marpet, are entrenched at those spots.

So that leaves right tackle, where Gosder Cherilus started for most of 2015 before Demar Dotson reclaimed his usual spot near the end of the campaign, after returning from a preseason knee injury.

The question heading into free agency was whether the Bucs would see that experienced duo as having right tackle well covered, or whether they believed an upgrade at the position was necessary.

Well, no additions at the position in the first month of free agency indicated the Bucs' position on that issue, and Koetter made it more evident when speaking at the Annual Meeting. Demar Dotson will go into 2016 as the starter and the Bucs believe he will regain the form that made him the team's most consistently effective offensive linemen from 2012-14.

READ: DOTSON IN AT RT AS O-LINE TAKES SHAPE

The Bucs made one big move on the offensive line in free agency, and that coupled with Koetter's statement on Dotson helped the O-Line depth chart fall largely into place. Cherilus will still try to win the right tackle job back from Dotson, but if not he will fill that important "swing tackle" reserve spot. As the offseason progresses and the Bucs pinpoint where they're most and least healthy along the front line, Pamphile's role will be clarified. He is capable of filling in at all five spots, including center, where he has drawn some work in practice.