BOSTON -- Defense has been a focal point -- both good and bad -- for the Boston Bruins this season.

Depth, trades, inconsistent play, injuries and call-ups have all made headlines for the first 20 games of the 2014-15 season. At the start of training camp, general manager Peter Chiarelli raved about the organizational depth on defense. That depth has been tested time and again this season, and it's also one of the reasons the Bruins are surviving one of the worst injury-plagued campaigns in recent memory.

"We really felt we had some good depth on the back end, and it's showing now," said Bruins coach Claude Julien. "Whoever we bring up seems to be doing a decent job, and a lot of guys that are here now are going to make it difficult for us when it's all said and done. There's a pretty good competition going on again on our back end."

When Chiarelli traded defenseman Johnny Boychuk to the New York Islanders prior to the start of the regular season, some observers thought the Bruins would struggle on the back end, a notion that gained steam after captain Zdeno Chara suffered a torn ligament in his left knee on Oct. 23.

It certainly didn't help when Kevan Miller suffered a dislocated shoulder and Torey Krug missed four games with a broken pinky finger.

Boston has had its difficulties on defense, but the additions of Joe Morrow, David Warsofsky and Zach Trotman have helped neutralize those deficiencies. Morrow has been the most consistent during his nine games. Warsofsky played only four games after his recall from Providence before suffering a groin injury and remains sidelined. Trotman also played nine games; he was recently assigned to Providence but then quickly recalled after Bruins defenseman Adam McQuaid suffered a broken thumb Tuesday. McQuaid will miss six to eight weeks.

The young defensemen's presence is turning Matt Bartkowski into a better player. After spending the majority of this season as a healthy scratch, he played the best game of his career Tuesday against the St. Louis Blues. Obviously, watching younger players earn the opportunity over him helped motivate Bartkowski.

Morrow, a former first-round pick (No. 23 overall) by the Pittsburgh Penguins in 2011, has played well for the Bruins. He's known for his offensive ability, but he's been reliable on defense.

"Things are going pretty solid," Morrow said. "Just trying to keep things simple, stay in the lineup and contribute in a way that I haven't really contributed before, kind of the whole defensive aspect of things."

He has helped calm the Bruins' early-season woes with his hockey sense, his consistency and his ability to move the puck out of the zone. Morrow possesses a big shot and won't hesitate to pinch in the offensive zone when needed, but his sound two-way play can be relied upon by management, the coaching staff and his teammates. He's finally seizing his opportunity.

But once Boston's entire blue line is healthy, management will have some difficult decisions to make.

"Your first game can either make or break everything," Morrow said. "If you come in here and don't live up to expectations, or you don't play as well as they thought you were going to play, then it definitely sets you back a couple of paces."

Morrow wants to prove he can cut it on this level and wants to leave a lasting impression that he can contribute in Boston for a long time.

Morrow and Trotman have played well for the Bruins. Boston isn't pleased with its start to the season, but the team remains in contention in the Eastern Conference and Atlantic Division because these players have made significant contributions on defense.

"It's a huge step forward for our organization, and having so many guys that they can count on and rely on to play big minutes for us," said Bruins assistant captain Chris Kelly.