It's crazy how people "takes" on trades are all over the place. It's like we can't understand the difference between looking at it "at the time of the trade" and "in hindsight"
Dorion was desesperate to re-sign Stone, even if he knew it would have needed to be under "Melnyk conditions" (lower term, lower salary and/or lower signing bonuses). He tried until the very end, that's why he signed him to that 1 year deal. So much was uncertain at that time, but in the end he just couldn't compete with what other teams can offer. In Stone's case, it seems it was only Vegas so Dorion didn't have any leverage. He was still able to get a 19 y/o guy that was a recent 15th OA pick and who has been regarded as a top prospect by every source. Being certain of how good or bad he will be is like saying "the Sens are going to win the Cup in 3 years". At this point, it is WAY too early to have any idea.
That trade sucked because you should never trade a guy like Stone in his prime (26 y/o), and frankly the return should have been more similar to Karlsson's but wasn't because the context sucked. To improve that "context", Dorion would have needed to give up on trying to sign Stone much earlier and trade him the previous year, before he became an upcoming UFA.
An Ottawa Senator GM under Melnyk is working under extremely hard conditions vs his peers. If that 2018-19 seeason went better and the ship would have started to turn around, things ould have been different and maybe Stone, Duchene and Pageau would still be Senators. Hard to fault the GM for trying to keep his players.
Regarding the Karlsson trade, it was a good trade from the start. It sucked that it was only for futures (because at the moment, we didn't know about the amplitutde of the rebuild) and that DeMelo was the only D-man in the return, but in terms of pieces, it had the potential to be a really good return.
That you like or not, Norris and Balcers were 2 very good prospects that could still grow. A 1st round pick is always a good piece and while it was not garanteed that the Sharks were going to miss the playoffs, there was a chance (that seemed likely to me at least, as you can see in my post history). And luckily for us, they struggled real bad which in the end gives us the 3rd OA pick in THIS draft, which makes it an incredible return. Plus two 2nds and Tierney are also good/decent pieces. And DeMelo was better than expected with the Sens and even returned another 3rd. This is a homerun trade no matter how you put it,
Karlsson was going to be a generationnal D-man but fate kinda changed his destiny. The injury from Cooke and the one in 2017 slowed him down. He should still be a very good D-man for years but he won't be as dominating as he could have been if it wasn't for these injuries. It was known when the trade happened. We didn't trade a generational D-man, we traded an elite offensive D-man.
Edit : oh and Brassard... He was not a "fading asset" at the time, he was coming off back-to-back 60 pts seasons while being a HUGE playoffs performer. He started fading in Ottawa but 2 years later he still returned a top goalie prospect, a 1st round pick and a decent veteran D-man (who returned another 3rd)
Saying/thinking that Brassard was a crap/fading asset when acquired shows a total lack of understanding of the NHL market. The trade sucked because we gave up on Zibanejad who was much younger and who could still break out (and he did), the Sens obviously didn't have much faith in this to happen. If he never broke out like he did and stayed the player he was, there wouldn't be anything to cry about, the Penguins return for Brassard would have more than made up for it.