I started playing MWO, on a lark, in February of 2024. As of a few minutes ago, I finally crossed into Tier 1 pilot rating. I'm sure there were probably more optimal ways of accomplishing this, including not dorking around with sub-optimal builds for a long period of time.
The thing I wanted to share was that the climb involved different mechs along the way.
At one point, I was at 0 pilot rating. Like, 0 in Tier 5. Not even a single pixel bar worth of rating. I used a Warthog Adder with HMGs and a Flamer to climb out of Tier 5 and into 4. I used a bunch of Urbies (mostly the K9) and Hunchbacks to climb out of Tier 4 and into Tier 3.
From there, it was mostly a lot of time in a Jenner JR7-A, the one with 0 cooldown with a single binary mounted. That thing was hell on wheels as a flanker. That took me into Tier 2 where I stalled.
I ended up switching to another Urbie, the UM-IIC-M with LMGs and double heavy lasers which took me through Tier 2 and into Tier 1.
I had seen it written somewhere that you need to consistently end up with a match score 250+ and I was no exception.
What I think is an interesting observation is that some builds just become a lot less viable as you move up certain tiers. Builds I would see all the time just kinda... disappear as you move up tiers. LRM boating still exists, but it's a lot less common. I haven't seen a Grasshopper in ages.
So if you find yourself wanting to move up and getting stuck, maybe it's not your pilot skill. Maybe you're just in the wrong mech for the tier you're in.
This is just all my observations, your mileage may vary, etc etc etc.