My daughter's serve is one of the most consistent in her HS league. Many of these girls on this level try to hammer the ball as hard as they could and the result is double fault after double fault. Instead of trying to hit a 100mph serve like many of the girls, My daughter hits her first serve around 60-70mph consistently.. and rarely double faults. Having said that, my daughter is a 4.0 and she subs in a 3.5 league every Thursday and there is not a person there who would get even a game off of her so I don't agree with your hypothesis. Although I'm basing this on what I'm seeing on Thursday nights. You might make the argument that there are stronger 3.5 leagues were you are but from what I've seen here, a strong serve is not going to tip the scales enough to beat a 4.0 player with a weak serve.