The 36-year-old, a 14-year NHL veteran, went 13-4-0 with a 2.45 goals-against average, .919 save percentage and three shutouts during the regular season for Pittsburgh, which signed him to a two-year contract this offseason to back up longtime Penguins starter Marc-Andre Fleury.
But Fleury has struggled in this series, including allowing six goals on 24 shots in a 6-4 loss on Long Island in Game 4 on Tuesday that evened the best-of-7 series at two games apiece. That ballooned Fleury's postseason goals-against average to 3.40. Since a shutout in Game 1, Fleury has allowed 14 goals in the past three games, losing two.
Vokoun will be making his first appearance in the Stanley Cup Playoffs in six years.
"We brought Tomas Vokoun in to play big games for us and be a goaltender we could count on to go in and play big games," coach Dan Bylsma said. "He's done that this year for us and he has been very good against the Islanders in three games he's played against the Islanders. We're getting a guy who's real capable at going in and has been a great goalie for us."
Thursday will mark the first time since 2001 that the Penguins begin a playoff game without Fleury between the pipes. He has started every postseason game the franchise has played since 2007, going 45-34 with a 2.72 goals-against average, .903 save percentage and six shutouts in 79 games.
But after leading the Penguins to consecutive appearances in the Stanley Cup Final in 2008 and '09 -- famously stopping Nicklas Lidstrom as time expired during Game 7 in Detroit in 2009 to clinch the Cup for the Penguins -- he has been mediocre.
Pittsburgh has won one playoff series since the 2009 Final and has lost three consecutive series to a lower-seeded opponent. The No. 1 pick of the 2003 NHL Draft has gone 7-10 with a 3.21 goals-against average and .883 save percentage over his past three postseasons.
Since shutting out the Tampa Bay Lightning in Game 1 of the Penguins' conference quarterfinals series on April 13, 2011, Fleury is 6-10 with a 3.68 GAA and .864 save percentage in the playoffs. He has allowed four goals or more in 10 of the 16 games -- notably allowing 26 goals in six games of a conference quarterfinal loss to the Philadelphia Flyers last year.
Before Bylsma announced Vokoun would be starting Game 5, Penguins captain Sidney Crosby expressed support for Fleury on Wednesday.
"Obviously, we know it was a tough night," Crosby said. "I think we've all had tough nights; for us, when we have a tough one, it's not quite as obvious as when the goalie has a tough one. He's won a Stanley Cup and has a ton of experience. He's shown numerous times he can bounce back so we have confidence in him, for sure."
Also speaking before Bylsma informed the media about the decision to start Vokoun, Penguins veteran forward Pascal Dupuis, after being asked directly about Vokoun, made it a point to say, "Marc-Andre is our guy right now."
But Dupuis also expressed confidence in Vokoun, who is 28th in NHL history with 300 career regular-season victories.
"We're definitely confident in both our goalies," Dupuis said. "Obviously from what you saw in the season both guys played really well for us."
Fleury went 23-8-0 with a 2.39 GAA and .910 save percentage during the regular season but has a 3.40 GAA and .891 save percentage during the playoffs. He is signed through the 2014-15 season.
Although Fleury partially is to blame for his poor numbers over the past two postseasons, he also has been the victim of playing behind a team that has adopted -- or been forced to adopt -- a wide-open, end-to-end style. Pittsburgh leads this postseason in goals and led the Stanley Cup Playoffs last season in goals per game despite the first-round exit. Also, multiple Islanders goals in this series have been deflected off the skates of Islanders players or Pittsburgh defensemen.
Still, even as the turnovers, giveaways and scoring chances for opponents have piled up, Fleury has been the most visible lightning rod for criticism.
"It definitely bothers us," Penguins forward Chris Kunitz said. "We're a team in there, and we support each other. Any time one of us is taking heat, it's a team sport and a lot of us on the ice are creating turnovers that lead to odd-man rushes and shots on net. The game is turnovers -- when you do something wrong, the other team always seems to come back around to score.
"So it's something that we have to be better in front of our goalie. If it's going in off skates and things like that, you can't control all that stuff. But you want to show that you have pride in your teammates and you want to go out there and you want to work harder."
Vokoun has appeared in two playoff series in his career, losing both, while with the Predators in 2004 and 2007. He is 3-8 with a 2.47 GAA, .922 save percentage and one shutout in 11 postseason games.
In the regular season, Vokoun won nine of his final 10 games, allowing one or fewer goals in six of his last nine starts. He was 3-0-0 with a 0.90 GAA, .970 save percentage and a shutout in three starts against the Islanders this season.
Vokoun set the Penguins record for a goalie shutout streak with 218:48 of scoreless play late in the 15-game winning streak this season. During that March run, the Penguins were proud of their defense-first mindset that led to a stretch of nine goals-against during an 11-game span.
They've allowed eight goals over the equivalent of the past 4-1/2 periods against the Islanders.
"It's about us playing better in front of our goalies," Dupuis said.