Hitting a Wall as a Player and as a Captain

[ChaosChao]

So I know I've posted on here rarely but I need advice on getting better as a backliner. I'm a consistent S+ player but it's always low S+ and my X power is average at best (I've only gotten over 2000 power one season and that was only for Splat Zones, peak was about 2150 or 2175). I don't feel like I'm improving and now I'm questioning if I'm even playing remotely right anymore. Any advice for that would be helpful. Additionally, I'm trying to be a captain of a team but it feels like not everyone on the team is practicing outside of our main practice times (be it playing or reviewing replays on their own or the like). I even financed a coaching session with Gem (Squid School) and while I felt it was beneficial, I feel like some team members aren't fully taking the coaching to heart and are making the same errors over and over and not consciously thinking about it.

So for both improvement as a player and as a captain, what should I do?