There are about 130 plays per game, and 256 games per year. That is 33,280 plays to analyze each year. That would increase to about 135k if you include Division 1-A college games. If you had two guys spend 15 minutes analyzing each play (2 guys to reduce errors) then it would take 20 full time employees to do this each year. More if you want to get more immediate results after each week. There are plenty of ex-athletes that couldn't make the pros and are intelligent enough for the work. Probably somewhere around $2 million per year in salary ($500k if you only look at professional games).
And for each play, you have 44 athletes whose performance needs to be evaluated according to specific metrics for multiple categories.
Let's look a one typical, very simple play: a running back dive through the strong-side B-gap with the fullback lead blocking out of a standard I formation. I'm not going to do this by each position, too much space, but here's a quick overview of the stats that would need to be collected:
Offensive line: Snap, blocking efficiency. This is complicated by blocking schemes (chip blocks, zone-blocking schemes, etc).
Fullback: Lead blocking -- did he clear the hole? Did he make a block at the second level but miss a free LB? Should he have blocked that LB at all, or was it someone else's missed block?
WR group: did they sell the decoy route, or make the block on the CB?
QB: Pre-snap activity, receiving the snap, handoff.
RB: Receiving the handoff, yards gained, yards after contact, depth of contact (none of which are the direct result of only his actions).
Defensive Line: block-eating, gap-filling, penetrate, containment: what's his responsibility? How do we know? If the weakside DE didn't fill his gap, but it didn't matter to the result of the play... is that scored at all? How can you determine if he filled the gap when he never had to get off the block?
LBs: Reads, shucking blocks, tackling, containment.
Safeties: positioning, reads, shucking, tackling.
Cornerbacks: reads, shucking, closing, tackling.
A football play is just far too complex to boil down to numbers for each position, since there are so many possibilities for what a player is supposed to do and how they fulfill their responsibilities.
So say you just look at the handful of players directly involved in a play... say, ten of them. Do you just look at the yards gained? How do you account for things like down and distance factoring into the style of play? A 2-yard run on 3rd-and-1 is much more valuable than a 4-yard run on 2nd-and-10... so how do your statistics weight that?
Long story short: unless the GMs office understands that statistics are a source of information, and not the be-all and end-all of player value, I can't see this being successful... scheme, coaching, other players are far too impactful on measurable results to make the stats definitive.