It depends on how you want to define a success but this front office is one of the few that have actually threaded the needle on a re-tool. That's essentially what they did the first 2 years of Sweeney's tenure. Reset the cap, treaded water for a few years, then were built back up into an elite team. Never got across the ultimate finish line but by and large they've been a top 5 team in the league for like 7-8 years running.
I've said my piece on the drafting thing. I think they are better than average they just haven't had any high picks and also have traded a lot of picks. 9 Sweeney draft picks were on the roster in the post-season. None of those players were selected in the top 10 of their draft, 6 of them were drafted outside the first round. Compare that to Toronto who bottomed out for the Shannaplan, they have 5 Shannahan era drafted players on their roster, 3 of them were top 10 picks (Mattews, Marner, Nylander). And they've never won a game outside of the first round. Edmonton is looking good but they had like 10 years of last place finishes and lottery picks to work with including multiple lottery wins allowing them to select the best player in the world. Colorado is a recent juggernaut that was built through the draft, but it took years of bottomling out to land MacKinnon (1st), Rantanen (10th), Landeskog (2nd) and Cale Makar (4th). The bottomline, IMO, is it's really really hard to find cornerstone players in the draft outside of picking in the top 5-10 for multiple seasons. There just aren't McAvoy's and Pastnrak's sitting the late teen's and twenties every year that this front office is constantly whiffing on.
As far as Monty goes, this was only his 2nd full season behind an NHL bench. I'm not sure it's prudent to write him off entirely. It's very difficult to coach in the post season. Sometimes coaches push buttons and it turns things around and they're hailed as a genious. Other times they push buttons, it doesn't works, and they are nevous nellies who panicked. Last season we criticised Cassidy because he was slow to react and make adjustments. This year we're mad at Monty because he threw the lines in a blender, it didn't work, so it looks like he panicked. I think he deserves another crack at it, I'm not sure they'd find a better option among the retreads on the market.