Turns out that all of the speculation that I was seeing (and participating in) Friday night wasn't on the mark. No upper body injury for Jaroslav Halak - the puck off of the mask that made him bleed a bit was not the reason that he didn't finish the game. He wasn't concussed, and he didn't need massive amounts of stitches. No, he has a lower body's injury that he sustained on this Henrik Zetterberg breakaway goal:
Nasty stretch. Halak has strained his groin, and will be on the short-term injured reserve. He's expected to miss Tuesday's game against the Nashville Predators and Thursday's rematch against the Detroit Red Wings. The Blues have recalled Jake Allen from the Peoria Rivermen, who has had a meh season at best. He as a 2.94 GAA and a .903 SV%.
If Halak were on long-term injured reserve, Brian Elliott would absolutely have to stay sharp for a while, or else the Blues'd have to make a move. Allen isn't Ben Bishop.