Eaglair has an ability that doubles its speed, effectively bringing its base speed up to the 180 (I think) range. Neon's reasoning was that any more than 80 would just be overkill. Certain evolutions lose base stats upon evolving, such as Kakuna to Beedrill and Shellgon to Salamence. In this case, it shouldn't even really be noticeable, since Eaglair will have MUCH higher speed than Gashawk in almost all cases.