1. Tangibles or measurables to get started ( but not necessarily the end).
Speed & Strength(Combine type+ HS Track/field etc,) , Height, weight.
2. Highlight film assessment (vision, cuts, acceleration, ability to shed blocks, reaction, etc.,)
3. Total Game Film assessment (same as above, also adjustment to situation or opponent, effort, etc.)
4. Intangibles, grades, love for the game, work ethic reputation, perhaps view athlete in other sports.
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*5. The staff's professional opinion of who really is a player, based on their experience and knowledge at this level
*6. The staff's ability and knowledge of understanding their system and being able to pinpoint and find players to fit their system to a T.
Here is how I understand it in general. At numbers 5 and 6, coaching becomes an art, not a science, thus the talent of the HC, and his staff, becomes crucial over time.