Apart from Boston 2018?
It's been analysed to death but the core of it is that NA CS focuses too much on individual heroics or executions whereas EU focused heavily on mid rounding and small team plays (i.e 2/3 person treats). Astralis changed how the game was played and NA never caught on to it. The 2 times an NA team got high again later were Liquid and NRG/EG and both times it was insane individuals carrying them but its not consistent for tournament to tournament.
I think it'd have to be both strat development and growing talent. It doesn't matter how good your strats and players are, sometimes you will still lose due to the minutiae of the game. You have to ensure you're going to get as many chances as possible at the trophy which means you need to ensure you're going to have top end players permanently.
Basically you have to play the percentages, it's what Astralis did and they've had the most prevalent era of any team.
CSGO was uncontested by Valorant in eSports until 2021. NA collapsed in CS because players demanded ridiculous pay for average performance and orgs started pulling out. As a result orgs that remained only picked up tried and tested players instead of developing homegrown talent which led to teams aging and getting worse.
The only region that actually had a player base issue hindering their growth was APAC in CS. Solo spent his entire career working on it in Korea and AUS likely would have done something crazy if they had more players/orgs to keep their scene active.
Na talent spread across many different games and there hasnt really been any good development programs or academies. So when the star players of back in source and go eventually became older there weren’t enough people to come and take their place and develop the scene more since no one wants to invest in cs other than Jason lake (complexity founder). Especially after Valorant released, there isn’t anyone playing cs in na that is really young like a monesy or a donk. It doesn’t help that the leaf situation happened which made na tier 2-3 put under scrutiny for cheaters and match fixers.
Talent spread was an issue everywhere imo. The development scene was the big issue but it was to do with where NA orgs out their funding compared to EU orgs.
Imo the match fixing issue was earlier than that considering iBUYPower happened. Remember although he wasn't involved in the scandal, one of the teams members was in the only major winning team for NA. If the match fixing didn't happen maybe that IBP team would have achieved a lot more.
North American societial values leans much further from video games, expecially competitive video games, compared to other regions. Different systems put into place, whether it be deliberate or not, punish youth for being into video games - both in social settings and financial settings. Just playing games is seen as a red flag to many millennials; the hobby is seen as childish. That is why you see much more success from NA in the valorant space compared to counter strike. The bulk of Gen Z is overwhelmingly flocking to online spaces due to those previously mentioned systems. Games are being seen as less male and less childish. Gaming is actually morphing into a hobby and a safe space, rather than something toxic and socially isolated. All of this removes pressure from young gamers with high skill ceilings who wish to go pro or even just to present themselves as high ranked gamers. This is really the first generation in North America who can be confident in that aspect of themselves. I doubt that NA has the playerbase to challenge other developed regions in Counter strike, but I assume that more and more modern games will have solid or advanced NA scenes compared to games from 7-10 years ago.