I’m no doctor, but I tore my acl in college. Had several grade 2 sprains on both ankles in high-school. To this day, my ankles are never 100% and at risk of being sprained all the time. My knee is stronger than before the injury. The worst part about an acl is it raises your chances of tearing the other one from using your 1 leg for a couple of weeks and you can overcompensate during recovery (knock on wood, I avoided this and had a great physical recovery therapist). But, if it’s an ankle he likely will be back on the field a lot faster. Really just depends.