Colleges like students with high GPA's, even the college coaches because there are more scholarships available to them. If you are a dump jock, you better be VERY VERY good if you want a scholarship. Committment, dedication and hard work exist both in the practice room and in the classroom. A kid with a high GPA shows good character and values. A kid who just slides by does not.
By the way, all four of my kids are the "babies" in their class. They all have summer birthdays; 6/28, 7/20, 7/21, 6/8. My oldest son, a freshman, is actually younger than half of the 8th graders. The only time you notice is when his friends are all driving and he has to hitch a ride.