Entering the season, the Bruins expected to be one of the league’s stingiest teams.

In front of two veteran goalies, coach Bruce Cassidy could deploy the 6-foot-9-inch reach of Zdeno Chara, the two-way skill of Charlie McAvoy, the ruggedness of Kevan Miller, and the size and mobility of Brandon Carlo. Erasing enemy forwards would be simpler than spraying Raid at a hobbled hornet.

However, none of those stalwarts have been available full time. The Bruins have been relying on the back end of their rotation and a few Providence B’s to lead the league in goals against, as of Dec. 1.

Entering Saturday’s 4-2 loss to the Red Wings, they led the league in goals against (60, or 2.40 per game). Their five-on-five allowance (32) was also best in the league, and eight fewer than the next closest club (Anaheim, 40).

Impressive, considering . . .

■ Chara (left MCL) last played Nov. 14, leaving the Bruins without their No. 1 shutdown option, and best penalty killer. He could miss another three weeks;

■ McAvoy (concussion symptoms) has missed 18 games, and dealt with vestibular issues while slogging through the first seven. He appears close to a return, though both club and player have offered nothing definite;

■ Miller had a 13-game absence (broken hand). After taking a puck to the throat Monday, he is likely to miss another month;

■ Carlo, who returned Saturday and skated 17 minutes 39 seconds, sat the previous nine games with a shoulder/collarbone injury;

■ Otherwise significant losses have seemed minor. Torey Krug missed most of the offseason and the first 11 games rehabbing a busted ankle. John Moore (three games) and Matt Grzelcyk (two) have spent time on the shelf;

■ Top prospect Urho Vaakanainen, an emergency recall last month, played two games before Ottawa’s Mark Borowiecki delivered a concussion blow. His date of return is unknown;

■ Cassidy has relied on players outside the projected top seven: Steven Kampfer has played 15 games, Jeremy Lauzon 13, Connor Clifton seven, Jakub Zboril two.

■ Moore, Grzelcyk, and Krug have logged between 21 and 25 minutes of late. Moore is a big body and a strong skater, and Grzelcyk has quick feet and a sharp stick, but neither has been asked before to shut down top forwards. Krug’s primary role is to create rushes, not defend them;

■ Boston’s best 200-foot forward, Patrice Bergeron, has missed the last seven games with a rib/sternoclavicular injury, owing to a hit from Dallas’s Radek Faksa. Bergeron, who could miss three more weeks, lifts the Bruins in every area.

The goaltending has been excellent, with Jaroslav Halak leading the league in save percentage (.936) and Tuukka Rask (.917) ranking 18th, entering Saturday.

The surprises are Lauzon and Clifton, neither of whom has looked out of place.

Boston was optimistic the rookies would be reliable performers, but not this soon.

“They’re not looking for autographs out there,’’ Moore said. “They compete hard, and play our system to a T. I don’t know where we’d be without their contributions.’’

The Bruins are 4-2-2 starting with their game inDallas, the night they lost Bergeron, two days after Chara’s knee buckled in Colorado. They are becoming comfortable in overtime and shootouts, with points in four extra-time games in that stretch (2-0-2 in those).

They’d like more punch, but they’re at ease with one-goal games (the only two-goal results of the last eight: 4-2 losses at Toronto and against Detroit, both via empty-netters).

“We’ve been doing some good stuff defensively,’’ David Krejci said before Saturday’s loss. “We’ve had some tough luck around the net. I feel like it’s coming. At the same time, to win games 2-1, 3-2, those games are going to make us stronger.’’

After the holiday season, the Bruins may be gifted with blueliners should Chara, Miller, and McAvoy remain on schedule. On Saturday, with Carlo returning to join Krug, Moore, and Grzelcyk, Cassidy hoped to develop a little continuity.

“Let’s enjoy it for tonight and see where it goes,’’ he said.

Bumps and bruises

Cassidy had no problem with the second-period bump Detroit’s Luke Witkowski landed on Krejci, who was not available to the media after the game.

Krejci said before the game he was checked for a concussion Thursday, after Islanders defenseman Thomas Hickey KO’d his tooth. It is unclear if Krejci was examined after Witkowski decked him.

“I think it was clean, again,’’ Cassidy said. “[Krejci’s] usually pretty slippery . . . The last two games he hasn’t been as aware, I guess.’’

Opponents, clearly, know that Boston is missing all that beef on the back line. Cassidy wondered if his players are being targeted in the absence of Chara and Miller, two veterans of the NHL’s police force.

“Detroit tonight, it’s probably the most fire I’ve seen in their group, coming into this building, in a long time. They’re usually not nearly as spirited. It’s been a while,’’ Cassidy said.

“I don’t know if that has something to do with they’ve changed a little bit of their group, or if it’s, hey, Z’s out, Miller’s out, Bergy’s out [and] they smell blood.’’

Karlsson on watch

Jakob Forsbacka Karlsson was the extra forward for the second game in a row. He is likely to stay the weekend in case someone falls ill, Cassidy said. Seeing the NHL game live will help him, and should motivate him. But “we wouldn’t wait forever’’ before sending him to Providence . . . Moore logged a yeoman’s 25:52, his team-high fifth time going past the 25-minute mark . . . Ryan Donato landed six shots in just 12:10 of ice time . . . Krejci put eight attempts on net, but lost 10 of 15 draws. As a team, Boston won 37 percent . . . Kampfer was a healthy scratch.

Follow Matt Porter on Twitter at @mattyports