Why is it so hard to break into the NFL?

Overseas-born NFL players like Osi Umenyiora, Efe Obada, Christian Scotland-Williamson, Christian Wade, and Rees-Zammit have shown that latecomers to the sport can succeed. Scotland-Williamson, a barrister, found NFL playbooks more challenging to learn than law books. Wade discussed the intimidating but methodical process of learning NFL playbooks, while Rees-Zammit navigated his way through multiple playbooks during his NFL journey.