The main one is that the older players who were also better quit the game, or didn't play as much leaving more room for players to improve while mixing in with old veterans who still play. Drift & his squad were a great example of this, when he first joined the league he was kind of a shitty noob on Deviak's trash squad, as older players left he started playing with MarsVolta/Maddux and gained a lot of experience, and when they left, he used said experience to make a pretty competitive squad. Same goes for me when I was on CF/NB.

WD started being shit after they added people like Bowen (love u) to their starting lineup

USL 8 or 9 might have been tough, but it wasn't the toughest. Yes, you had players from other zones coming to USL, but that was because the zones were condensing, which forced those players to find other leagues to play in. Seasons 1 - 8 had nothing but original players from the original KR map. Nothing is harder than competing against players that played on the same map day in and day out. They knew the map inside and out. It came down to who had the better players. Then they started changing the maps and that is when Semper Fi capitalized by using naders, and for a short time snipers.

I'd say most leagues peaked in their earlier years myself, probably most leagues, if not all of them were at their best like seasons 3-6 give or take. My reasoning is a few different things. 1) The first couple of seasons strategy and gameplay were still undecided for a lot of people. 2) You had a lot more players than the later seasons. 3) This is also about the time stuff like big resos and mousing and voice chats entered the mainstream. That's not to say someone from Season 10 couldn't mop the floor with someone from Season 5. But they were different eras. Also, I can probably speak a little about WD falling from perennial top4 to more of the middle. Players simply just quit. xT and Jejo were beasts at the time for example. xT quit at some point and Jejo joined Final Fate. And there were other players who either quit or definitely played less. Happened in a lot of leagues around that time. The earlier dominant players got their wins and stopped trying as hard or simply quit all together. My 2 cents.

I think it's nostalgia bias, I can tell you people had a lot better aim/reactions in season 13 than they did season 3. And that's with me being able to dodge/aim better myself

As technology changed in computers, so did the game and how it was played

That's because those players had 13 seasons to get better hahaha