I don't hate the player, I hate the move.
There is a huge difference.

You don't know the cost on the other end as far as the prospect coming in. Who would have been 19-20 years old. Not 28.
So you brought in a middle 6 guy, for 2 years on an average middle 6 contract. You can find that in FA. But the prospect you can't.
That is really the issue here.
This team is going no where in it's current build. At best it's a pretend playoff team. Where even if they get in, it's clear they don't have the talent to win.
The only place you are going to find the talent to boost the team is in prospects. As they are cheap, and allow you to spend in FA to make those last 2-3 year push.
It was simply a bad move going forward to think the roster player was more important than the prospects. That is the issue.

But wait you'll see this next year. Don't think Crosby can drag a team forward kicking and screaming for 82 games. He can't and it's taken a super human effort from him to get them where they are right now.
Eventually that effort is going to dry up. Which is why a 17 game sample doesn't mean anything.
As far as Rakell, no one would say he's having a good year. It's looking pretty bad. They should have moved him after last year. Zucker was a huge mistake. There is no point arguing that. He was Brassard 2.0.
Carter should never have been traded for, he was slow the day he got here. Another Hextal move that trashed this team the second he got his hands on it.

As far as Dubas you can't look at anything he's done and say it's worked. Crosby is making him not look like an absolute clown right now. Trading for EK was a huge mistake. 10 mil in cap, and almost pissing away a top 10 pick. He has no business moving draft picks. It will be another massive mistake for him to try to move another 1st round pick. But you never know, he might be dumbas enough to do it again.

Anyone looking at SJS with Burns and EK should have known you can't put two guys like that on the same defense. It didn't work in SJS and it wasn't going to work in PIT with EK and Letang. He needs his own team to actually get value from him, not splitting time.