I don't have the exact numbers but height and weight also contribute to speed so there are other variables but pending everything is the same the difference between 14 and 25 is 11.
I know that with a 10 difference between 15/25 defense and 25/25 the guys with 15 have a 74 Lateral Quickness and block/steal while the guys with 25/25 have like a 94 Lateral Quickness and block/steal. Should be around there, I might be mistaken but gives you an idea.
With the difference of 11, maybe 22 or so attribute points difference in terms of 14 agility versus 25.
Honestly though a post scorer is not trying to fly by his opponent, he's trying to post up he doesn't need 25 agility.