Should Miller return against Detroit, Cassidy said it would likely be either Connor Clifton or Jakub Zboril that would be the healthy scratch, though both have acquitted themselves well during their first two varsity games.
Clifton, who has displayed an energetic, rough-and-tumble style while playing with Torey Krug, has quickly gained the trust of the coaching staff. The 23-year-old has averaged a tad over 19 minutes of ice time to go a long with a plus-1 rating and 11 penalty minutes (he fought Stars forward Jason Spezza in his NHL debut on Friday).
Zboril has averaged just under 11 minutes of ice time while alongside Steven Kampfer on Boston's third pairing.
"I don't know, we'd have to discuss that," Cassidy said of which player would sit. "Zboril was the last one in, so we could certainly then balance the pairs. We'd still have three rights - Clifton, Miller and Kampfer. So probably one of those two guys.
"Wouldn't be [Jeremy] Lauzon. He's been steady, we're happy with his game. Obviously Torey stays in, [Matt Grzelcyk] will stay in."
Cassidy also said that John Moore, who flew back to Boston on Sunday to have his lower-body injury further evaluated, is unlikely to rejoin the team on this trip. He was not asked about the status of Brandon Carlo, who has been out for the last four games with a lower-body injury.