Bubble fatigue cited as mental challenge during NHL playoffs

Dallas Stars head coach Rick Bowness looks up to Dale Hawerchuk as he is honored before NHL Western Conference Stanley Cup playoff action against the Calgary Flames, in Edmonton, Alberta, Tuesday, Aug. 18, 2020. (Jason Franson/The Canadian Press via AP)

St. Louis Blues' Robert Thomas (18), David Perron (57), Ryan O'Reilly (90) and Brayden Schenn (10) react after losing to the Vancouver Canucks in an NHL Western Conference Stanley Cup playoff series game, in Edmonton, Alberta, Friday, Aug. 21, 2020. (Jason Franson/The Canadian Press via AP)

The Dallas Stars celebrate the win over the Calgary Flames after an NHL Western Conference Stanley Cup playoff hockey game, Thursday, Aug. 20, 2020, in Edmonton, Alberta. (Jason Franson/The Canadian Press via AP)

St. Louis Blues goalie Jake Allen (34) pulls the puck out of the net as the Vancouver Canucks celebrate a goal during the second period in Game 5 of an NHL hockey first-round playoff series in Edmonton, Alberta, Wednesday, Aug. 19, 2020. (Jason Franson/The Canadian Press via AP)

Washington Capitals captain Alex Ovechkin, second left, and teammates Ilya Kovalchuk (17) Tom Wilson (43) Nicklas Backstrom (19) watch the closing moments of the third period against the New York Islanders in an NHL Stanley Cup playoff hockey game in Toronto on Thursday, Aug. 20, 2020. (Nathan Denette/The Canadian Press via AP)

Dallas Stars defenseman Andrej Sekera (5) and goaltender Anton Khudobin (35) celebrate the win over the Colorado Avalanche in Game 1 of an NHL hockey playoff second-round series, in Edmonton, Alberta, Saturday, Aug. 22, 2020. (Jason Franson/The Canadian Press via AP)