The one season the Leafs had Ceci and Barrie on their blue line they were bottom 5 in the league for goals against ... and then improved massively once they dumped both the next year. Makes you go "hmmmm".
Last time I checked, Barrie and Ceci played in the final four last spring, while the Leafs as a franchise haven't been there for 21 years.
The Oilers have generally done well in the Ken Holland era, with respectable / solid finishes:
2016 -- .427 -- 7th place
(10th year in a row missing playoffs)
2017 --
.628 --
2nd place (
lost second round)
2018 -- .476 -- 6th place
2019 -- .482 -- 7th place
Holland hired:
2020 -- .
585 --
2nd place (lost weird bubble / qualifying round)
2021 --
.643 --
2nd place (lost first round)
2022 --
.634 --
2nd place (
lost third round)
We can probably now see 2016-17 as a bit of a fluke season where suddenly some third and fourth-line pieces (and Pat Maroon) fell into place magically, at the same moment Draisaitl broke out and Talbot had his best season. Obviously, it wasn't sustainable... or maybe it was if Chiarelli hadn't traded away every winger on the club. 2018 and 2019 were completely "lost" seasons, which, as a fan, I'm still angry about years later.
Holland is a GM who's been around the block and wants to go for the win 'now', and isn't really interested in the rebuild of the rebuild of the rebuild... I'm okay with that, and I think the fanbase deserves the club to go all-in right now, which they are, and they had considerable success last spring. (I still think if the Makar 'onside' call wasn't idiotic and if Nurse and Drai weren't crippled, the Oil would have pushed Colorado to the brink.)
However, the clear danger of the 'all-in' approach is that if you sign one crippling contract to the wrong player, you're really in trouble (in the cap-era). And I think we can all see the Nurse contract as having the potential to be that crippler.
There are things about Nurse I like (his physical skills / skating are excellent, and he used to be kind of mean), but honestly I was sort-of hopeful that they'd trade him back in 2021 when the contract was up. His value was high then, and obviously Holland and his team gambled that Nurse had taken the big step up to becoming a near-elite NHL defenseman and that it was worth over-paying him to get that #1 Dman locked down. However, 1.5 years later, it appears that gamble was a loss. Had they traded Nurse in 2021 and gotten another Ceci and another Niemeläinen (or whatever), I think the D-core would be a lot more solid today than it is.
(The Campbell signing also at present looks bad, but I still think Campbell might come back to form and surprise everyone. Anyway, the price of the two goalies in tandem isn't too bad. Skinner has been great.)
So, in general, I think Holland and co. have had the right approach and they've mostly made good moves. I mean, every GM is going to lose some gambles here and there, but in moves like dumping Lucic and turning that into Hyman, and in acquiring and locking down Kane., etc., I think Holland has done well enough with the forwards.
But the defense core is just not getting it done, and they need some help. I'm afraid the Nurse contract is going to be the crippler for the next... oh, six or seven years.