You forgot their one major flaw - goal scoring. They are playing great defensively and Halak has been awesome but they are currently ranked #26 in the league in scoring.
They aren't going very far if they can't score.
I'm not forgetting anything. I am well aware of their offensive problems. They've had scoring problems the past couple seasons.
Ownership knows that they will have to make a move to pick up some more offense. My guess is they are waiting to see how good the younger players are going to be to see exactly what they need to pick up. And Perron, Oshie & Co. have all gotten better over their first few years in the league...and this year is no different, they are better than the year before. Once this team establishes itself as a legitimate playoff team, I can see them making a move.
The Blues are a very young team and their best players should still have their best years ahead of them (Johnson, Perron, Oshie, Pietrangelo, Backes, Berglund, Polak, Halak)...and throw D'Agostini into the mix who has been a great surprise. Talk about flat out stealing a player from another organization...we should trade with Montreal more often. Our last two acquisitions from Montreal have been D'Agostini and Halak...for essentially nothing.
The loss of Oshie for at least 3 months really stings. He's the most dynamic and versatile player on the team. And it might not be a huge deal had the Blues not already been hit hard with the injury bug. Perron, Carlo, Jackman, & Polak are already out with injuries. Within a few games they lost a bunch of good players.
But the last few losses aren't overly surprising. You can only lose so many players and still play at a high level. Detroit knows this because of their injury issues last year. They flirted with missing the playoffs for most of the season until they got healthy late in the year. Hopefully they can play .500 or better hockey until they get some of their players back.