I don't think Colorado has improved that much. Particularly with Toews, he's an elite defensive defenseman don't get me wrong. But he's probably the worst of the NYI 4 at defending the north/south game. He can move the puck pretty well, and I think people like that, but I think people are missing the point when they look at that, because that's what they already have. What they need is the ability to stop teams from dumping, battling, cycling, and then positioning in front of the net. They make much of the fact that they were 6th in GA in the regular season. But when they ran up against a good North/South team in Dallas, they couldn't stop the rain. And no matter what you think of Dallas, there will be copycats. A lot of teams both in free agency and in the draft, you can see the attempts to recreate a Dallas Stars. If you can't stop the North/South game, and you have these teams trying to build a contender on a budget who play a north/south game, maybe it won't be Dallas who you face but you will still need to learn to be good at it.
And if I thought Toews was going to replace Girard then I'd think "oh yeah this makes them way better." But by all accounts the plan is to replace a Ryan Graves or if not Graves then Erik Johnson with Toews. Graves is underwhelming for what his kit would suggest against the North/South game. But he's not the root of the problem. The root of the problem is that you have this system built around the transition and breakouts and gap closing on defense and forcing forwards entering the zone to let go of the puck, which is what they want. The Colorado defensemen are good against that, but they're not necessarily good at stopping say dirty goals. And if they don't build to be better against that, I think they just run into the same problem. Toews can be part of the solution, but they have to identify the problem to begin with.
Saad is a good player and helps, but I believe in diminishing returns on offense. Puck possession is a finite resource, and you can increase it or you can increase your efficiency with it, but the bottomline is that the introduction of a new forward doesn't increase the total amount of puck possession time for each forward, it takes away time from other forwards to create a pool of puck possession time for the relevant forward. Saad is very good. I don't know that he's so much more productive than Donskoi that the team as a whole is just going to score that much more.