Bouwmeester plays a lot like Pietrangelo in the defensive zone. They both use their big bodies to take the puck away from opposing forwards. First, instead of only going for "the big, punishing hit", they make their hits, useing their full bodies, positioned carefully to be in the optimum position to allow them to get their own stick on the puck and have the momentum of their hit move their own body between the opponent's body and the puck. The opponent's body is then pushed away just as their stick frees the puck from the oppont's stick. Meanwhile, Pietrangelo or Bouwmeester, with head up, and still well balanced on the ice, is starting to skate free, ready to skate up ice, or make a break-out pass, while the opponent has been knocked off balance, and can't keep The Blue defender tied up, and can't get back to him.
I've seen this happen hundreds of times with Pietrangelo (more last season than this), and by Bouwmeester in his 2 Blues' games, and in the few games I've watched with him as a Flame. The forward skates towards The Blues' net with the puck and Pietrangelo (or Bouwmeester) make a full-body hit, while at the same time, extending their stick out to share the puck with the forward, and the followthrough of their contact moves the puck off the forward's stick, and the force of the collision sends the forward off-balance off the puck, and The Blue defender, well-balnced on the ice, continues skating off with the puck on his stick.
It's not a body-crunching open-ice, punishing hit, like some of the famous biggest, toughest and meanest defencemen are known for, but it is very effective in breaking up potential scoring chances, and gets The Blues' rush started faster than needing a second Blue to get to the loose, freed-up puck on a "punishing hit".
Despite the fact that Pietrangelo and Bouwmeester are not known for initiating a lot of contact, and not making a lot of punishing hits, they are very effective in using their big bodies in defending their own zone.
At least last year, Pietrangelo never shied away from contact. This year, I've noticed that he's sometimes been slower to react to opposing forwards entering his zone. But, I think this is due to his doing too much "thinking" as opposed to just naturally acting by instinct as a defender. I'm not sure, but I think this may have come from his trying to add more offence to his game, possibly by thinking of how he's going to start the rush after taking away the puck, instead of just defending against the forward.
In any case, Bouwmeester seems to defend in all zones, pretty well, despite his spending a fair amount of time carrying the puck into the offensive zone and going in deep to help in his team's offensive flurries. In his second Blues' game last night, there were even a few instances when both he and Pietrangelo were deep in a cycle behind and near The Jackets' net, and yet, they both got back on defence in plenty of time after The Jackets started their rush.
I think their tandem will allow The Blues to increase their offence greatly, and, yet, will also provide The Blues with much better defence against the opponents' best scoring forwards, as opponents will no longer be able to pressure Pietrangelo's partner into forced errors, as Bouwmeester can bring the puck up ice with confidence, or make the needed safe pass under pressure.