BOSTON -- Boston Bruins fans had a steadily building roar every time another biographical clue appeared on the Jumbotron before Game 2 of the Stanley Cup Final against the St. Louis Blues on Wednesday night, from the career coaching record to the Super Bowl championships.

So when New England Patriots coach Bill Belichick appeared, waving the Bruins "fan banner" high above his head, TD Garden was positively thunderous.

Standing with Special Olympian James Coffey, Belichick uncharacteristically grinned as he waved the flag, part of a pregame tradition in Boston. While a giant Bruins banner is passed around the lower bowl of the arena by the fans, Boston luminaries wave a smaller flag, from local sports icons to Boston natives to inspirational figures such as survivors of the Boston Marathon bombing.

Among the Patriots who previously waved the fan banner were former tight end Rob Gronkowski, wide receiver Julian Edelman and center David Andrews.

Boston sports teams have traditionally shared support during playoff runs, from wearing each other's gear in interviews to public expressions of good luck. Bruins coach Bruce Cassidy reached out to his fellow coaches before the Stanley Cup Final for advice, including Belichick.

"Terrific, terrific guy. Very insightful. He was great," Cassidy told 98.5 The Sports Hub last week. "They've been very good to share whatever they can, very supportive. We practice different than football. There's the mental side of it that's important: how to keep players on their toes and don't let their mind drift and get their focus back. I think that was more the discussion than anything."