If by Boston dressing Maroon it forces the Leafs to dress Reaves they've won that mini-matchup before they even drop the puck. Especially on the road.
What is Reaves purpose? Protect the big 4 from sucker punches, slewfoots and elbows? He'll have a tough time doing that from the bench. If you have the Matthews line out against the Maroon line I absolutely love that. If we put out Reaves so he can take a run at Pasta or Marchand, Bruins absolutely love that. It's multi-level thinking.
Regular season that's fine, playoffs dress useful players. Every second Reaves is on the ice Boston is more likely to score a goal