I shot sports with a 300 f/4 for a while. Loved the IQ but it was often too short. I moved to a 400 f/5.6. Loved the IQ and the length but it was sometimes too short and other times too long. I eventually picked up a 100-400L V1. While the 400 prime is sharper and slightly higher contrast than the 100-400L, it really doesn't matter in real life photos of HS sports players. I sold the primes and stuck with the 100-400L. The versatility of the zoom is just too compelling even compared to the slightly better IQ from the prime.