I think those are great dividends. The alternative was cap hell. I'm not really sure it's fair to break down Senyshyn, Zboril and Debrusk separately either. We have no idea which one the Bruins would have taken if they only had one pick (my guess is that it would have been Zboril, given the D situation at the time). So you could probably add Debrusk to that list.
If they had just one pick (there own at #14), if he was available it's Zboril, if not it was Debrusk. Remember now in between each pick teams can still contact the Bruins to make deals. So they were taking the guys they wanted in the order of preference. It would be moronic to not take them in order of preference. So I'm not adding Debrusk to that list, because we don't know if Zboril would of been there at #14.
The "cap hell" stuff was grossly exaggerated. Lucic was off the books in a year anyways (and they still pick up a sizable portion of his final year). They wanted to keep Hamilton (hence the contract offer his agent never replied to) but Hamilton alleviated their "cap hell" situation essentially the minute he decided he was done in Boston.
Long-term these deals might end up paying big dividends, I'm not disputing that.
But short-term they have done very little to help the Bruins win hockey games in the now 3 seasons and 5/8s of another since those deals were made. I said it at the time that Sweeney made a mistake not getting at least one decent player (so Top 9 F or Top 4 D-man) in either deal for a team trying to stay competitive. Even one solid player would of helped then and now.