That's not how trades work! You can't just say "yup, give this guy away and we have cap room"! Your whole concept of how trading works is warped. Just because the Leafs retained 1.25M, it doesn't mean they would've retained more to make a trade with us, and they CERTAINLY weren't willing to take back any significant salary.
DD as a salary dump/buy-out? Buying him out would make our cap issues even less manageable, and I'd like you to find a team willing to take on Desharnais' contract without giving us a contract in return. No, the likelihood that the Habs take on Kessel's contract is so extremely miniscule, that when you factor in other teams with more cap space and assets to trade, the possibility is almost non-existent. You make trades seem so easy "trade this guy, buy out this guy, TA-DA! Cap space!" It's not that simple, especially for a star like Kessel.
Again, many people suffer from this issue. They think that trades are so easy to make, and that's why so many people are so angry at Bergevin. They think it's so simple, and he should've managed to get a top 6 forward easily! No. That's not how any of this works. There are 30 teams in the league, all of whom ALSO want cap space and top 6 forwards. There's a possibility Bergevin could've made a couple of trades/moves in order to make space to acquire Kessel, as you suggest, but then after all of that, where is the guarantee that our offer can beat Pittsburgh's? Or the other teams that wanted him?There isn't. It's just not as simple as you imagine it being.