Doesn't really fit what the Blues are looking for. The only reason they'd deal Stewart is because they cannot afford him. Boyle is really expensive. Even if San Jose ate a bunch of his contract, 1. he's a righty, 2. they're probably looking for a steadier defensive d-man, and 3. the Blues are really unlikely to deal impact youth if youth isn't coming back. If they're dealing youngsters for experience, it'll be guys who aren't key parts of the team yet.
A deal around Pavelski or Vlasic makes a lot more sense.
Sharks do this to get a good young winger to play with Couture.
Blues do this to get one of the top Dmen in the league to play with Pietranglo
Why would we want a right handed defenseman as the basis of a trade when we have Pietrangelo and Shattenkirk. The downgrade to Clowe from Stewart this year would be horrible. Do you know just how good Stewart has been this season?