The Tampa Bay Buccaneers have published their first depth chart of 2016, and the most important line on the page comes right underneath the header. That line reads:

"(Subject to change.)"

With their preseason opener just five days away, the Buccaneers were required to put out a first working version of their depth chart, but there's little doubt that it is still a work in progress. The team is only about halfway through its 2016 training camp, with four preseason games still to go, and position battles continue to rage all over the field.

"Everybody's battling," said Head Coach Dirk Koetter, who would probably prefer not to print a depth chart until September. "All 90 guys out there are battling. Don't make any predetermined 'who's going to make it, who's not.'"

In other words, take it with a grain of salt as you click here to check out that first depth chart of 2016.

Even with its malleable nature, the depth chart does offer a few clues as to how camp competition is shaping up. For instance, as noted earlier this week, second-year tight end Cameron Brate has achieved first-team status for now. Wide receiver Adam Humphries, identified by Koetter as the team's third wideout on Monday, is listed right behind starter Vincent Jackson. If there was a designation on the depth chart for a "slot receiver," Humphries would occupy the first line.

Here are a half-dozen additional observations regarding the Bucs' first depth chart of 2016:

1. Tight ends are doubling their footprint.

As anticipated, the Buccaneers have removed the "FB" or fullback designation on their depth chart and are instead listing two TE spots. Brate is atop one of those lists and Luke Stocker is atop the other. This draws a more accurate picture of what the Buccaneers were already doing on offense, even before this year's training camp. Tampa Bay opened with two tight ends on the field in 10 of its 16 games last year, and Stocker started a career-high 14 contests even though he was only occasionally targeted in the passing attack.

Rookie Dan Vitale, who played a hybrid "superback" role at Northwestern, is listed behind Stocker on the depth chart. Third-year player Austin Seferian-Jenkins, who was last year's opening-day starter, is behind Brate and is still battling to regain that front-line designation. The Bucs have eight tight ends on the depth chart and Koetter thinks that a good number of them could be useful in the regular season.

"I'm really fired up about the versatility of all of our tight ends," said Koetter. "That tight end group, that's a position that we're deep at and those guys are making plays every day. We're asking a lot out of them and they're giving it to us right now. So not just Dan, but I'm fired up about a bunch of those guys. Our preseason is going to be good for some of those younger guys."

2. The center competition is still neck-and-neck.

Joe Hawley and Evan Smith – essentially the 2015 and 2014 starters for Tampa Bay at center – started camp in an even battle for that spot in 2016. Apparently, the coaches are not yet ready to declare a winner, or even a leader, in that battle. On the depth chart included in the Buccaneers' release for next week's preseason game in Philadelphia, the first line at center says, "Joe Hawley or Evan Smith." They are presented on the Buccaneers.com depth chart in alphabetical order.

3. Kenny Bell joins Adam Humphries in the second column of receivers.

Koetter has said on several occasions that the competition for the rest of the spots on the receiving corps – whether that's two, three or four players – remains wide open. For now, however, Bell is listed behind Mike Evans across from Jackson and Humphries in the other receiver spot. If Bell wins that job he would likely be the first option to step in if either Evans or Jackson were unavailable, putting his skills to use as an  outside receiver while Humphries remained in his slot role.

4. William Gholston joins Robert Ayers as the first defensive ends listed.

While this is an accurate reflection of what has been evident on the practice field, it is probably not particularly descriptive of what the Buccaneers will be doing with their defensive linemen this season.

Expect a healthy rotation between the seven or eight D-linemen that are active on any given game day, with certain packages designated for different situations. For instance, the Bucs have executed a lot of practice snaps over the last nine days in which the four-man line features Ayers moving into the middle to join DT Gerald McCoy, with Noah Spence and Jacquies Smith coming in as the ends. This would appear the team's optimal lineup in pass-rushing situations. Gholston should see plenty of reps, too, as he has consistently been drawing snaps at both end and tackle.

5. The rookies are going to have to earn it.

As much impact as the Bucs are hoping to get from the likes of Spence and cornerback Vernon Hargreaves, the first depth chart does not list a single rookie starter. Roberto Aguayo, the only placekicker on the roster, obviously occupies the top spot at that position, but the kicker is not technically considered one of a team's 22 starters.

That said, Hargreaves, and Spence, as well as Vitale and fellow sixth-round pick linebacker Devante Bond are all listed as second-teamers. Fifth-round pick Caleb Benenoch, who has been sidelined by a leg injury, has been moved to the back of the list to reflect his injured status. That's also the case for guard J.R. Sweezy and linebacker Cassanova McKinzy.

Undrafted rookie Luke Rhodes is listed as the second-team middle linebacker behind Kwon Alexander.

6. Adam Humphries and Kenny Bell top the kick return lineups.

In addition to getting that third-receiver nod, Humphries is also the front-runner to win the punt return assignment. He's joined on the depth chart by fellow receivers Bernard Reedy and Jonathan Krause.

Bell, who returned kickoffs at Nebraska but missed his 2015 rookie season due to injury, is followed on the depth chart at that spot by safety Ryan Smith and then Reedy and Krause. Though Humphries and Bell appear poised to get the first in-game reps in the return game, those jobs will ultimately be decided by the results from the four preseason contests.