sure, I get all of that. But you never said before that 'I' in your MgR/I equation is (as you call it) 'effective swingweight'. And if it is - than aren't all your line of thinking based on observed correlation between ATP player's racket specs and MgR/I of those rackets kind of baseless? Since I'm pretty sure that all data about player's rackets refers to what commonly is known as 'swingweight' and not 'effective swingweight'? Also, isn't saying "In most cases, the difference between measured swingweight and "effective" swingweight is consistent enough that it is not worth worrying about the difference." a bit misleading? As you pointed out yourself - if you add weight to the sides of the racket the 'effective swingweight' actually changes apparently noticeably. Isn't adding weight to the sides of the racket like at least as common as adding the weight at the top or bottom of the racket? In other words 'most cases' is like 50% of the cases, no?