"It's always difficult when you're not playing, you're always trying to get back into the lineup," said Vatrano. "But when the team is as hot as it is right now you've got to tip your cap to everyone in the room, even if you're not in the lineup you're rooting for the guys. You want them to win, you always want to win.
"You've got to be a good teammate, whether you're in the lineup or out of the lineup. For me, I just have to have the same mindset night in and night out."
At the same time, Vatrano had to stay prepared, knowing that he could be inserted back into the lineup at any time. That time came last Thursday night in Ottawa with both Brad Marchand (suspension) and Noel Acciari (lower-body injury) unavailable.
Vatrano slotted into Acciari's right-wing spot on the fourth line and played 7:10 while landing one shot on goal alongside Sean Kuraly and Tim Schaller. With Acciari still day-to-day, Vatrano will play in his second straight game on Tuesday night when the Bruins host the Anaheim Ducks at TD Garden.
"I actually felt pretty good," said Vatrano. "I've been trying to stay on top of my conditioning, on and off the ice. I felt good, felt like I really didn't miss a beat out there. My timing was good, so hopefully I can add some more finishing to it. Obviously in a different role right now, so trying to be reliable."
Despite taking two penalties in limited ice time, Bruins coach Bruce Cassidy was pleased with Vatrano's overall effort against the Senators.
"I thought he had his legs, was trying to be effective on the forecheck, created a couple turnovers, got some pucks to the net with that line. He got into trouble with some stick fouls and we made the decision to shorten the bench late in the game. Other than that, we were pleased with Frank," said Cassidy.
"Obviously he'll stay in tonight and hopefully he can build off it. We didn't have our expectations too high because he missed a lot of time. He's young guy, and they're to used to sitting that long unless they're injured. It's a tough spot for him and I thought he handled himself well."
Cassidy acknowledged that Vatrano - a talented offensive force - can still improve his game on the other side of the puck.
"With Frank, we're going to continue to make sure that in those close games he does his part away from the puck, keep getting better defensively and hopefully the puck falls a little bit and he creates a little more on his own on that line," said Cassidy.
"He's been good, he's worked hard the last six weeks without playing. I give him credit for that, it's not easy when you're young."
Vatrano, who was a goal-per-game player in the AHL, said he won't be changing his mindset despite playing in more of an energy role on Boston's fourth line.
"I just try to play the same way I always do. You're on the fourth line, you're in an energy role, just trying to make disruptive plays, nothing really changes, you've just got to be more reliable on that fourth line," said Vatrano. "You don't know how many shifts you're gonna get throughout the game. You've got to go hard every single shift, whether that's getting hard on the forecheck or trying to create plays for your line mates out there.
"Schallsy, Kuraly, and Noel have been doing a good job on that fourth line this year, so with Noel being down with an injury it's time for me to step up and play that role just like he did."
