Hockey is back, and the Boston Bruins will begin preparing for the 2015-16 NHL season Thursday at Ristuccia Arena when training camp begins.

There’s more uncertainty surrounding this year’s camp than perhaps any other in head coach Claude Julien’s decade-long tenure with the team. Many prospects and AHL players, many of whom represent the future of the club, will be competing for roster spots at forward, on the blue line and in net. Very few positions in either of these three categories are set in stone.

What should you watch for at camp over the next few weeks? Check out the primer below.

Schedule

Camp begins Thursday, Sept. 17 with off-ice testing, which is closed to the public.

On-ice practices begin Friday, Sept. 18 and run for 15 straight days through Oct. 2.

Practices at Ristuccia Arena are open to the public. The only TD Garden practices open to the public are Saturday, Sept. 19 and Sunday, Sept. 20. Practices at Ristuccia are Sept. 25, 26, 29 and 30, and Oct. 1.

Players To Watch

Forwards

Aside from Patrice Bergeron and Brad Marchand playing on the first line and David Krejci centering the second line, pretty much every other forward spot is up for grabs. A lot of new players will be entering the lineup, and finding trios that produce the best chemistry will be a challenge for Julien.

Here are three forwards to watch:

Brett Connolly, RW: Connolly suffered an injury just days after the B’s acquired him last season and was limited to five games. He has a powerful shot, fights for pucks in dirty areas and goes hard to the net. His power-forward style makes him a good option for Krejci’s line.

He’s also highly motivated on a one-year contract and aiming to prove the Tampa Bay Lightning were wrong to give up on him.

Ryan Spooner, C: After finishing last season with 18 points in the final 24 games — easily the best stretch of his NHL career — Spooner will be under a microscope all season. He has the offensive skill, power-play ability and speed the Bruins will look to incorporate more of this campaign.

Spooner likely will slide into the third-line center spot for the departed Carl Soderberg, where he might reunite with David Pastrnak.

Matt Beleskey, RW: Boston’s marquee free-agent acquisition plays the tough style Bruins fans love, but it will be his goal scoring that determines his spot in the lineup. The B’s were 22nd in goals scored in 2014-15, and Beleksey will be relied on to provide 15 to 25 goals and fight for pucks in and around the crease.

He has the inside track to a top-six spot, but there are four or five right wingers fighting for that ice time.

Blue Line

B’s captain Zdeno Chara will take his usual spot on the first pairing, but the other five spots are open (Dennis Seidenberg, Adam McQuaid, Torey Krug and probably Zach Trotman are locks to make the NHL roster, but where they slot into the lineup remains undetermined).

This will create plenty of competition among the 10-plus defensemen in camp.

Torey Krug: Expect Krug to take more of a leadership role on and off the ice this season. Dougie Hamilton’s departure also opened up a top-four spot for Krug, which is a position he’s wanted to prove he can handle over the last two years.

His offensive production is very good, but he’s been sheltered from tough defensive situations throughout his career (73 percent of his shifts started outside the defensive zone last season, per War on Ice). It’s now time for him to play against better quality opponents and take on tougher defensive assignments.

Colin Miller: He was the only skater acquired in the Milan Lucic trade and his offensive ability (powerful shot from the point, puck-moving skill, playmaking skill on the power-play) could replace some of the scoring production lost when Hamilton was traded. Miller ranked second among all AHL D-men in scoring last season and should compete for a third-pairing NHL spot.

Kevan Miller: Expect less fighting from Miller this season after he injured his shoulder in a bout back in October. The injury bothered him throughout the campaign. Miller is on a one-way contract, but a strong case could be made that Matt Irwin, Colin Miller, Zach Trotman and Joe Morrow all are more deserving a top-six spot.

Miller, who doesn’t provide much offense and fails to drive puck possession, has as much to prove during camp as anyone.

Positional Battle of Note

The backup goalie job is going to be an intense competition with four players in the mix. Veteran Jonas Gustavsson is in camp on a professional tryout, and he will compete against young netminders Malcolm Subban, Zane McIntyre and Jeremy Smith for the role. McIntyre and Smith have yet to make their NHL debuts, while Subban has a little more than a period of NHL experience.

The Bruins need better performance from the backup this season to avoid Tuukka Rask being forced to play 70 games again. Rask handled the increased workload well, but it’s far from ideal for the No. 1 goalie to play that many games. Recent history shows playoff results are not good when a starter hits the 70-game mark.

My favorites for this role are, in descending order, Gustavsson, Subban, McIntyre and Smith. However, this could change significantly early in camp because there’s not much separating the four.

Thumbnail photo via Perry Nelson/USA TODAY Sports Images