I imagine it varies somewhat by sport and school, but the Harvard reader guidelines do specify an athletic rating number whose description includes the phrase " possible walk-on to a varsity team; has an IRF of a 4 from a Harvard coach" The regression analysis found that receiving this athletic rating was associated with a 4x increase in odds of admission, with all other application factors and reader ratings the same – roughly the same boost as occurred for applying SCEA or being SES disadvantaged. While this potential walk on rating does appear to be a significant admission advantage, it pales in comparison to the ~3000x increase in odds of admission that was associated with being a recruited athlete. They are completely different orders of magnitude.