Potentially controversial post:...
First off, most teams dont REALLY want to be a top team - this is fine. Paintball is a hobby and is for fun, take from it exactly what you are looking for - days out with your mates, banter, a few games with teams of a similarly low commitment level and standard. Everyone is happy. This probably covers at least 60% of teams not just in the UK, but worldwide.
When it comes to teams and players who do aspire to be a top team, I feel there is a lack of direction in most cases. Add in a HUGE amount of pride / personal history and grudges, and top it off with a little fear or lack of courage to just straight up ask how to be better and you start to get close to the root cause.
Just this season alone we (Nexus) have actually had multiple other UK Elite teams refuse to train with us seemingly because they would rather train with another team that is more their own level in order to win more points. And lets be honest, we havent even been that good this season.
When I was playing amateur level with Campaign back in 04-06 we would often drive the 3hrs+ from London to Bristol or Nottingham or Leicester and spend two days banging heads with Shockwave or OG Nexus. We'd normally only win a handful of points but we took so much from every single point regardless of the result, and we were able to tap in to the minds of the top UK players of the time as well.
When we win matches at CPPS, hardly ever do the teams we beat actually come and ask us how we were able to shut down their attack, or how we were making spots they weren't. I have actually been and told teams how we go about shooting a certain spot off the break if I see they are struggling and they have completely ignored the advice and continued doing what they were before with no success.
A lot of the posts in this thread are referencing money and sponsor control. I've never once been told who I could and couldnt train with, and I've not heard of this among any of the other teams we train with (including the ones who decline the offer - its not down to sponsorship) so I would be interested to know who this has affected and who made that call.
As for money, this is an all too easy excuse. Yes paintball is expensive and you have to be able to afford it BUT this is where a lack of direction comes in to play. A lot of teams feel that to improve you have to play a whole lot more, while this is true to an extent, with a little application and dedication/will power you can actually improve quite quickly at little EXTRA cost (time & money). Teams need to set goals - season goals and short term goals and goals for individuals. Then work back from there - if your back guy needs to shoot a higher percentage OTB then you set up a drill to work on it - start of with static targets and then build up to a runner, then add in a shooter back at him too for real-game simulation - he doesnt need to hose a loader on every spin. The same can be said for running and shooting, snap shooting, working in pairs etc. Yes, ultimately you need to build up to full points to put it all in to practise and this can be paint heavy, but with how much paint you would have saved up to this point you still should not be shooting much if any over your normal daily amount. Its not hard to sit down at the start of the season and make a realistic budget and a plan, then actually stick to it. It might mean having 1 or 2 less weekends playing over the season in favour making the weekends you do have more productive, but believe me its worth it when it pays off.
I could also go on about how pro schools are notoriously under-attended (mainly by those on these aspiring mid-level teams) compared to how many people sign up for pro tryouts, and many other elements too but i think I've ranted enough for now.