league is not too hard for sure. Getting to an elite level is completely different. There was a time when Canadian curlers could dominate the sport throwing rocks 2 or 3 nights a week at the local curling club. But when guys like Pal Trulsen from Norway and Pat Ryan from Alberta started focusing on athletic style training and throwing rocks every day things really started to change. The mindset now is that everyone on the team should be able to make whatever shot is necessary in any situation. The days of having the finesse guy or the power guy being set up to make their specific type of shot are going away. Timers and the Free Guard Zone/5 Rock rule have changed the game a lot as well. Now the guys who get to the Brier, the World Championships, and the Olympics are pretty much elite curlers. Rec league guys just can't make the complex, pressure shots that come up at the higher levels of competition.
Check out the Stone Cold episode of Losers on Netflix for a look at how Pat Ryan really altered the sport with his style of play.