Grzelcyk is currently in the NHL's concussion protocol, Joe Haggerty of NBC Sports Boston reports.

EDGE Analysis

Grzelcyk has been released from the hospital, but he won't make the trip to St. Louis with his teammates ahead of Game 3, so it's safe to assume he'll miss the Bruins' next two contests at a minimum. John Moore will likely replace Grzelcyk on Boston's bottom pairing for the foreseeable future.