We used to have a coach that would scream "buy back space" to the forwards when they didn't come back to help us out on breakouts. If we saw the names on the sweater and not the crest, we knew we would be in for a long game.
You are right, coaches have figured out Yeo's breakout system and can pressure the defense as the forwards have already turned and headed out.
The lack of support has been glaring at times.
Assuming a simple "up," I've always thought it was ideal to have the strong-side defenseman and winger supporting the play along the boards, with the center (or weak side winger if the center is trapped in deep) supporting closely through the middle of the ice. The weak-side defender either acts as a hinge or "over" option depending on how high the play is in the zone, or he can more aggressively exploit the weak side if a suitable passing lane develops.
The weak-side winger has a lot of options. He can either fly the zone early on a shallow angle (stretching the defense vertically and presenting a home-run option), or work ahead through the middle towards the strong side boards on a more pronounced angle presenting a number of options along the way while also supporting the play if the puck needs to be chipped ahead either to him or through him into the zone. He can shade toward the middle staying relatively even with the play, ready to support defensively if there's a turnover while trying to find a weak-side passing lane to present himself as a passing option...a more conservative positional option, but also one that applies far less pressure to the other team. I've never really been a fan of just sending the weak-side winger flying down the ice in his vertical lane.
The Blues have had their moments exploiting the weak side, but the strong-side play and support through the middle of the ice often leaves a lot to be desired. I wish I knew how much of the blame for that lay at the feet of the players, and how much to lay at the feet of the coaches. It's almost impossible to tell just from watching, but it's clearly a problem that needs to be addressed.