Allen started Game 4 in place of Brian Elliott, who started the first 17 games of the 2016 Stanley Cup Playoffs, and made 31 saves in a 6-3 win to even the best-of-7 series 2-2.
"I'm comfortable with either guy, but I woke up this morning, talked to the coaches again and decided to go with Jake," Blues coach Ken Hitchcock said Sunday.
The Blues were looking for a boost after being shut out in Games 2 and 3 to fall behind 2-1 in the series and turned to Allen, who split games with Elliott during the regular season.
"You need a good goalie, and we had a really good goalie playing, but we were relying on the good goalie all the time," Hitchcock said of Elliott, who is 9-8 with a 2.34 goals-against average and .925 save percentage in the playoffs. "We weren't playing for [Elliott]. We were relying on him, and there's a big difference. We needed to play harder for a goalie. It didn't matter if it was [Elliott] or Jake or whatever. [Elliott] was standing on his head and we were giving up too many quality scoring chances, too many easy chances, too many odd-man rushes and we were getting comfortable thinking, in my opinion, that the goalie could stop everything.