My casual (and perhaps not accurate) observation from an outside point of view is defense and center are positions that could be strengthened. You may have prospects that are ready to jump in and fill those roles though. I asked a question about this in another thread on this board. I don't think its a problem to have more options in those very important positions. Far better to have an abundance of options than the opposite.
Your observations are good, that's really the 2 weaknesses in the Sens lineup, particulary at center and also 2 big holes on defense with no #2 and no #3 after Chabot, which explains why the team is struggling defensively in some games. There's also several inexperienced players and not a lot of strong vets.
The good news is those are already potentially in the system
Logan Brown : still a big mystery, could pay off or end up somewhere else.
Tim Stutzle : will he be a Center? That basically changes everything
Shane Pinto : a guy that has started playing competitive hockey much older than others, has been progressive at an alarming rate.
Josh Norris : Already looks quite competent, will be quite competent
Nick Paul : I'd have him as my shutdown 3rd line center, he's smart and very good defensively, very good on face-offs
Colin White : struggling on face-offs, not everybody will get to play center so would be the logical choice to play on the Wing.
Who could fill the top-4 after Chabot?
Jake Sanderson : will be crucial for this team, could/should be an excellent #2
Artem Zub : already looks quite reliable, should be a good #3 or #4
Jacob Bernard-Docker : looks like a safe bet to be a 2nd pairing D-man
Tyler Kleven : could be a beast, looks good early
Erik Brannstrom : another safe bet to be a 2nd pairing D-man, needs to clean his game a bit, but is LD so there's already Chabot and Sanderson at that position.
Lassi Thomson : Belleville didn't play a lot of games but has been quite re-assuring so far, as to there's maybe something here. Good enough to be a 2nd pairing guy? Well, that remains to be seen.
Maxence Guenette : who knows with this guy? Has progressed well since being drafted
Zaitsev ain't bad but he's going on 30 y/o and ideally, you have at least 3 better D-men in front of him. There's also Wolanin who looked very promising 2 years ago but big injury + covid got him out of synch. I think he's going to have to re-prove himself somewhere else. If he's option, he's the guy I'd claim if I was Seattle.