From my POV The Tier 5/6 itself is mostly fun to play. Most T5-6 can also take on T7 ships. As a mainly solo playing average scrub, most of my T5/T6 cruisers I started after the MM changes look like this. The Ships I played before or other classes like BBs or DDs seem to have a much easier time within that tier range and can 'carry' a bit better.

I think we need the MM to consider not just the Tier itself, but rather to weight personal player stats more into account to create more balanced teams. Sometimes I checked both teams players stats and noticed there are certain imbalances that could have been avoided if certain players would have been switched between teams.

However, the most impact on these games is the player mindset itself and the lack of teamplay.

From my experience the avg. T5-6 looks like this:

BB captains reaching that tier having troubles to adapt to the slightly shifted 'meta' resulting them to play more passive, staying at (too much) range (IJN BBs), choosing routes that don't benefit the team (especially with the slow US/KM BBs), getting isolated, getting killed.

DD captains seem to try the sealclubbing they are used from T3-4, getting their 1-2 yolo kills in the early game, but are missing in the later game when they become actually really important.

Cruisers just getting rekt because of guns, no matter the angling. Since the team DDs are mostly dead already when arriving a cap, a cruiser captain is a sitting duck, harassed by a DD or/and just getting devasted from BBs without any support from his own.

If you dare to try to communicate with your team and make suggestions, you mostly just get flamed: 'stfu nub, I know how to play'.