The Blues made good draft picks and acquisitions that work for their team . Remember, the Blues did have only 1 top 5 draft pick on their team and thats Pietrangelo(they did trade Johnson away). They were middle of the pack when it came to the draft and drafted well ,especially their later picks too.
They had a plan in place for how they wanted to build their team and followed it very well. Hitchcock instilled a strong culture within the team and you see everyone following the system to a T.
Smart acquisitions over the years like Steen, Sobotka, Shattenkirk etc while also effective use of non top-10 picks to grab guys like Oshie, Schwartz and Berglund have led to them building the team they wanted to. These players were just seen as good cheap depth a few years ago but are integral to the team now in their own ways.
Blues have been able to find an identity, while the Leafs are still lost in the water, trying to navigate themselves on the right path.
They're kind of stuck in the middle of nowhere right now. Some days it looks like they're trying to follow the path of the Bruins or Blues where they have a gritty team with good goaltending, but the defense sucks too much to follow that kind of plan and the team is still really lazy and soft in many ways.
Then other days, it looks like they're trying to be more like Chicago or San Jose, relying on speed and skill. But again, crap team defense that can't cover for those high risk plays; if the forwards want to play this way, they need to have a commitment to back-checking and playing a strong 2-way game like players such as Hossa, Toews, Couture, Marleau, etc. all do.