John Moore replaced Grzelcyk in Games 3 and 4 against the Blues but had a shot-attempt percentage of 27.27.
If Grzelcyk and Chara are out for Game 5, the Bruins may be forced to dip deeper into their reservoir of extra defensemen. Veteran Steven Kampfer is the most likely candidate to play in Game 5, but it would be his first game since Game 1 of the Eastern Conference Final against the Carolina Hurricanes on May 9, when he replaced the suspended McAvoy. Kampfer scored a goal in that game.
Urho Vaakanainen, the No. 18 pick of the 2017 NHL Draft, played his only two NHL games with the Bruins in October. Cassidy said Wednesday that it would be a big ask to call upon Vaakanainen at this stage of the season.
The Bruins' most successful defensemen in the Cup Final has been Torey Krug. He's the only Bruins defenseman to play in all four games and have a positive shot-attempt percentage above 50 percent (51.08). He also is tied with Marchand for the playoff lead with 11 power-play assists.
McAvoy (24:24), Krug (22:02) and Brandon Carlo (22:02) lead the Bruins in ice time during the playoffs. The challenge facing them is whether they will be able to raise their collective games, under trying circumstances, to give the Bruins a chance to win two more games.
St. Louis has had an advantage at defense through the first four games of the Cup Final. With injuries hitting the Bruins defense, that advantage could be a determining factor in the rest of the series.
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