for anyone else reading the topic, this^ style is nothing new. i can think of several people whove been formulaically using the combine results & the range of the '04 default rookie ratings for several seasons already.l
i attached an example spreadsheet used to rate defensive rookies from one of these roster-makers. this is an early version & his actual formulas are protected per his request, but basically it's common sense: you can see that physical attributes (SPD AGL STR JMP, etc) are determined by the combine numbers within the range of the original 04 default rookies. positional skill attributes are valued based on his proprietary formula which weights statistics like sacks, tackles, INTs. there are even adjustments to consistency & composure based on whether the school was Div1A and/or from a major/power conference.
im not commenting on these rosters at all, just saying that ppl have been using this method since the game came out & have been releasing them for free.
attached spreadsheet courtesy of aaron54de, his rosters are available here:
http://mysite.verizon.net/vzeekp5y/index.html