He's just getting started, he has only had a bit of time with this group, they need more experience. Sid, Geno, Tanger and EK at 50 should hit their prime, so after a decade+ the Pens should be able to decide how good of a coach he is (still a small sample size so far).
There's 164 game sample size before this one that says no, he has no idea how to fix any of his issues as a coach of this team. He has 3 wins this season because of incredible individual efforts out of Malkin and Blomqvist. To get him to win again, you'd need to somehow find a prime Malkin and Crosby somewhere to mask his warts. The last 16 games last season, they went on a tear, but what was buried underneath all of that was that the Penguins scored at a ridiculously unsustainable pace (3.96) that led the league in that span but also allowed 3.34 goals against and were doing what they're doing now but without the scoring - which is bleeding chances against, turnovers, being reckless defensively.
The Penguins defense was never coached that well before this, there were times where the Penguins had very good goaltending for a few months that saved them games and made their defense look better than it was, but then when the goalies struggled and struggled hard, the defense wasn't really doing much of anything to bail them out or help. This season, having David Quinn who had the same ideas of how his team should play which didn't work well, is his assistant and now you have an Assistant that doesn't offer you a new perspective, but rather, the same one. So you have an AC that is telling you the system is fine because that's the only one he also knows and gives him confirmation he's on the right path so it must be the players again, for an 8th season in a row.
The issue is the GM's have gotten players Sullivan likes to use would work well with, theoretically anyway. But then he uses them and it's like he didn't even read their scouting report of what they did well for other teams, what they are good at, bad at, etc. He will use them how he wants and then when they struggle, act like they need to be better not that they couldn't succeed in usage they were never good in, for assignments they were never fit for. So you'd have a player that played a ton on PK units, he'd never play that player on the PK and throw them into a role that isn't really a good fit because in his mind - it should work.
He had this whole spiel about pairs - He wanted to have pairs on forwards, units of 2 and then change one of the players as needed, that was his idea to build chemistry and have the ability to tinker. Except that really only ever applied to Crosby, the rest were f***ed all over the place with random ideas for what winger should be where. He also prioritizes veterans over youth and acts like WBS has literally no one he can use, which isn't wrong but not even close to being entirely right. Last season he had Harkins play 45 games (0 goals...ZERO GOALS), White play 10, etc, but he had Gruden who was a far more effective player on the 4th line and could penalty kill, refused to give him more then a couple of games, Hallander left 2023 as he'd seen enough of the bias.
Imagine being so married to a player like Harkins because he does "something" the team needs but on the 4th line where at least most of the players on the 4th line for virtually all the teams has players that will mostly play on the PK. Harkins wasn't even good at that, but got 45 games. It's stuff like that, then his usage of Puustinen, how he kept playing Ruhwedel over players like Smith, PO Joseph, etc. Harkins isn't even an NHL caliber player and even Anaheim could see that, but not Sullivan. Players like Hallander, Puustinen, Gruden, etc aren't some fancy names, maybe they could be if they were used better, Hallander barely got a chance to even do that, Gruden shows he's capable of being a 4th line player at least and is strong on the PK, plays a smart 2-way game, Puustinen is a winger that you'd want to see more out of with better usage given the season he had last year (instead they didn't dress him for 6 games, then when they did - He was on the 4th line with Acciari and Hayes...). He healthy scratched Bunting while not trying him with Sid or elsewhere much at all, but then kept Beauvillier up on the 1st line for 6 straight games and then finally gave him the benefit of playing on a different line to see if he can do something. Bunting is a far better player than Beauvillier, while he struggled offensively, he was doing more to help his line than Beau was.
This team has overhauled so much of its roster since 2017-18, there's a ton of changes each year and each time a bunch of it's bizarre usages and implementing an archaic system that he doesn't really adjust at all and thinks the players are the issue for not being able to play how he wants, except they are playing his system and that is what it looks like. They routinely allow players to get to the crease without issue, the worst net front presence in the league, turn the puck over a ton, constantly get hemmed into their own end, overall team defense has been disjointed for a few years now, his idea of who works with whom has never made sense - Rust with Sid instead of Rakell as an example. The Penguins give up the most high danger opportunities in the league.
I think one of the funniest things said was by Bryan Rust - Something along the lines of how can the message get stale if there's so much overhaul with the roster?
The irony.