The Boston Bruins are still the odds-on favorites to win the Stanley Cup, at -118 at 888sport. But those odds have gone down steeply since Wednesday night - much like the number of healthy bodies on their roster.

Game 2 of the Stanley Cup Finals saw the Bruins lose a very important defenseman, Matt Grzelcyk, to a likely concussion after his head was hit into the glass by St. Louis Blues forward Oskar Sundqvist.

On Thursday, Bruins coach Bruce Cassidy told reporters Grzelcyk would not make the trip to St. Louis for Games 3 and 4, that he was in the NHL’s concussion protocol.

Here’s why those who bet on the Bruins to win the Cup should be much more worried about their chances right now:

Bruins Defense Already was Limping, But Now it’s Worse

Before these playoffs even started, the Bruins got the bad news that rugged defenseman Kevan Miller would be lost to a knee injury. He was in the Boston top-six as the regular season was winding down, but then the injury happened, and it appears he won’t be playing any hockey again until next fall at the earliest.

In the Eastern Conference Finals, Bruins 42-year-old captain Zdeno Chara couldn’t play Game 4 because of an unspecified injury.

The 10-day layoff between rounds allowed Chara to heal up enough to play Game 1 of the Cup Finals, but in that game he suffered a nasty gash to the left forearm from an incoming puck. Chara had to leave the game for a while and get treatment.

That kind of injury isn’t going to keep a warrior like Chara out of the lineup for long, but you have to wonder if it might not have affected his stick-handling somewhat. He played more than 25 minutes in Game 2, but finished a minus-1 and gave the puck away a couple of times.

Now comes the likely series-ending injury to Grzelcyk. While Bruins defenders such as Chara, Charlie McAvoy, Torey Krug and Brandon Carlo get more ink, Grzelcyk was a very important player to the Bruins.

He averaged more than 19 minutes of ice time during the regular season with Boston, a considerable amount. At even strength, his puck-possession shot metrics were strong, at a 51.5 percent Corsi rating.

At the time of Grzelcyk’s injury, with two minutes left in the first period, the Bruins seemed fine in their breakouts from the defensive zone and overall puck movement down the ice.

Without him the rest of the game, Cassidy had to juggle five D-men and Boston’s whole game structure went out of whack. The Blues took full advantage by pounding the five remaining D-men any chance they got on the forecheck.

The Blues were credited with 50 hits in Game 2, to 31 for Boston. With Grzelcyk out, Chara probably still not at 100 percent and Cassidy now having to choose between journeymen John Moore or Steven Kampfer as Grzelcyk’s replacement, you can expect the Blues to try and hit that much harder in Game 3 and beyond.

That will be even easier for the Blues to do with the next two games at home because, as NHL betting fans know, they will have the last change.

Others Up Front may be Hurting Too

Remember that intrasquad scrimmage the Bruins had last week, to try and stay sharp during the long layoff before the Finals? Despite the virtual no-hitting atmosphere of the game, Bruins first-line left wing Brad Marchand had to leave the game for a while after appearing to jam his left hand in a collision with teammate Connor Clifton.

Marchand said he was “fine” afterward, but his so-so performance thus far (one goal, an empty-netter) has people naturally wondering if he’s playing at less than 100 percent, especially being a lefty shooter.

Then there’s important Bruins forward Jake DeBrusk, who appeared to be in serious pain in Game 2 after taking a slash to a hand/arm from the Blues’ Robert Bortuzzo.

DeBrusk is the kind of tough player who doesn’t like to let anyone know there is pain, but he couldn’t hide it after taking the Bortuzzo slash. He was hunched over skating to the bench, a definite look of pain on his face. He finished out the game, but didn’t seem as effective.

All of this should give Stanley Cup betting fans pause about the Bruins. When a Stanley Cup Final series is tied 1-1, the winner of Game 3 has gone on to win the Cup 78.6 percent of the time since 1939 (22 of 28 times).

The Blues now have home-ice advantage in what should be a roaring Enterprise Center for Game 3 Saturday night.

The Bruins will be coming in to the Gateway City banged up. The Bruins remain the slight favorite overall, but St. Louis is favored for Game 3, at -127 according to the latest NHL odds.

I’d say that’s a good bet right now.