It’s not often you hear about an intriguing battle for the role of sixth defenseman in training camp.

However when mid-September rolls around, the Boston Bruins will have several players contending for the last spot on their defensive rotation.

The club likely has five spots on the blue line secured as of today. Captain Zdeno Chara, Dennis Seidenberg, Torey Krug, and Adam McQuaid are all guaranteed of roster spots with soon-to-be 25-year old Zach Trotman pegged by many to make the leap from Providence into the rotation.

The focus now shifts to who claims spot number six. There are several contenders who want to lay claim on that last spot with the Bruins come October 8. With training camp just over a month away, here are some of the defensemen to watch for.

Joe Morrow

Joe Morrow got a taste of the big time for the first time last season, playing in 15 games while captain Zdeno Chara missed time with a knee injury. The 22-year old scored his first NHL goal during his stint in Boston against Pittsburgh.

Ironically, the Penguins originally drafted Morrow in the first round (23rd overall) of the 2011 draft. It was a moment that couldn’t be scripted.

He possesses some qualities that general manager Don Sweeney wants from his hockey club this year. Hockey’s Future gives their assessment of Morrow.

“Morrow is a mobile and aggressive two-way defenseman who can play in all situations. His puck-distribution ability is top notch and he has a hard and heavy shot that typically hits the net. Morrow owns a high hockey IQ and does an excellent job of keeping his head up when moving the puck up ice and carrying it along the blue line.”

The 6’1 blue liner will get an extended look in training camp, hoping to avoid a bus ride back to Providence after spending the last two seasons there, scoring 41 points in 89 games.

Matt Irwin

Matt Irwin signed a one-year contract with the Bruins for an affordable $800,000 in early July.

The 27-year old is coming off an odd season with the San Jose Sharks. Irwin struggled prior to the All-Star Game scoring six points in 23 games with a minus-10 rating. Post All-Star break, he scored 13 points in 30 games with a plus-13 rating to finish the season strong.

Last month, I asked my colleague Andrew Bensch to evaluate Irwin’s ability.

“Inconsistent two-way potential. Decent size, above average in both zones, booming slap shot. His skating is not ideal. [Irwin] could be a top-four guy, but more likely a solid bottom-pairing option.”

His 153 games of NHL experience and above-average possession statistics (51.7 Corsi-For percent at even strength in his career) work well to his advantage in a Claude Julien system. Irwin is an under-the-radar candidate to earn his position.

Kevan Miller

Kevan Miller endured a difficult campaign last year. The 27-year old suffered two separate injuries to his right shoulder and missed 41 games because of it.

Miller’s shoulder injuries cost him half of last season. (Tom Szczerbowski-USA TODAY Sports)

Instead of being a lock for the Opening Night roster, Miller will have to earn his place amongst the rest of the field. The Los Angeles native is a rough-and-tumble character who isn’t afraid to play the body and engage in fisticuffs to spark the Bruins.

He’s mostly been a third-pairing defenseman in the 88 games he’s played with Boston, scoring 13 points with an impressive plus-40. Interestingly, his career Corsi at even-strength is exactly 50-percent, proving that plus/minus may not be the most reliable statistic.

Regardless, Miller has become somewhat of a fan favorite for his physicality. He’ll have to earn his place back on the Bruins roster after last season’s injuries.

Colin Miller

Colin Miller was acquired in the deal that sent Milan Lucic to LA on Draft Day. Regarded as one of the better prospects in the Kings system, the 22-year old had a breakout season for the Calder Cup champion Manchester Monarchs.

Miller ranked second among AHL defensemen in scoring with 19 goals and 51 points in 70 regular-season games and chipped in 10 more points from 19 postseason appearances. The Ontario native also won the fastest skater and hardest shot competitions at the AHL All-Star Game.

With a little seasoning, Miller could be exactly what the Bruins need, according to Hockey’s Future.

“Long-term Miller must continue to address his defensive game and work to add the strength and agility necessary to compete in the NHL. His progress to this point suggests he can be an effective lower pairing defenseman with the ability to contribute on the power play.

He is an intriguing prospect to watch as camp opens up next month.

The Verdict

All four candidates have some element in their play to suggest they will all see some playing time with the Bruins this season unless one of them blows away the coaches and management staff by the end of training camp.

Colin Miller has the most promise of the bunch after a strong year in the AHL but will have to learn an entirely new system. Morrow and Kevan Miller have a familiarity with how Julien works the rotation and the system he employs. Irwin has more NHL experience than the other three players combined.

It all sets the stage for an interesting battle to ensue in one month’s time.