He is, to put it simply, one of the best players in the world right now.
"I think once [Yeo] came in and we changed our defensive system a little bit, once Marty kind of took over and started communicating with [Allen] and [backup Carter Hutton], and once he got in his comfort zone and got his confidence he just kind of went with it," center Paul Stastny said. "He just seems a lot more controlled. He's an athletic goalie, but he's only athletic when he needs to be now. In the past sometimes he was maybe a little overaggressive, where now I think he can make the first save and rely on us clearing that puck."
Yeo was an assistant to Hitchcock before taking over as coach so he saw first-hand what Allen went through, how hard it was for him to struggle so badly, and it hurt because he also saw how hard Allen worked to get out of it, and how none of it was working.
No one would ever want to go through something like that.
But the Blues are benefiting from Allen's experience because, in a sense, what happened in Game 1 and how Allen bounced back in Game 2 was like a microcosm of his season, and maybe it doesn't turn out the way it did if he never had the difficulties he had in January.
"When we were going through that he was shouldering a lot of the blame, probably most of the blame, and we were all part of it," Yeo said. "But he took it, the same way he took it last game, and that, to me, is what winners do.
"I think that was an important part of his growth as a starting goaltender and a big reason why he's playing to the level he is right now and a big reason why he can respond after a game like last game."
Allen is back, but the full comeback story has not yet been written. Not if he has anything to do with it.
He would much rather have it end in June with a Stanley Cup being raised above his head.