It's never good when a player gets injured, regardless of if they're a core player or a 4th line sub-in guy. The Blues tend to have a knack for having more of the former get injured throughout a season than the latter. Look at the list: Jamie Langenbrunner, Vladimir Tarasenko, Alex Steen, Andy McDonald, and now T. J. Oshie. Unfortunately for the Blues, they may be short every single one of those five players tonight against the Phoenix Coyotes.
No further concrete updates have come out of the Blues other than that he is listed as "day-to-day." No information on possible call-ups has been released either, though if you see that the Blues have recalled someone from Peoria, Oshie's more than day to day. Call-ups are never a good sign.