The last regular(Lucic) to wear a green jersey at practice was scratched the following game. What makes you think that the same won't happen? I can't think of anything. Why wouldn't you practice with the lines you plan on playing?
See my previous post. Julien said the lineup isn't set.
The coaching staff doesn't just throw guys out on the ice in a playoff series. They consider everything - how players are practicing, how they're feeling (illness, injury), what the matchups are, how certain players/combinations have performed against the opponent, and vice versa, the current state of the opponent, and on and on it goes. I would believe that following practice today Julien and his staff are putting in a significant amount of time working out various scenarios, and it will continue tomorrow. And throughout the series as well.
Sometimes I wish HBO would do a 24/7 on the Bruins so people would realize how much work these guys put in. They're not assigning players roles based on how much they like them and then going out and having a few beers. It ain't the '70s anymore.
Addendum - this isn't addressed to you, specifically, Patty. I know you know better.