What was theoretical about it were the two values that follow the equals sign. However, we now know the equation looks like this:
YPA = 74% (yards in the air) + 26% (yards after the catch)
...versus something else (theoretically), where YAC is thought to be weighted more heavily than a mere 26%.
First of all, your formula makes no sense. I think you really did fail algebra. There is no "weighting" of anything. Simply:
avg YPA = (Avg yards in the air) + (avg yards after catch)
I think you are trying to say that on average passing yards (and therefor YPA) is made up of 74% yards in the air and 36% yards after catch. But, you wouldn't even compute it using "league wide" correlation (or whatever you did). You'd simply do the math (addition, subtraction, multiplication, division), by game, by QB, or league wide.
Those ratios may very well be accurate BUT that does not mean YPA and YAC are "largely independent". In fact, one is used to compute the other. You don't need stats to figure that out, just common sense and algebra.
so...... :blowup:
You've tried to make two points in this thread:
1. YPA is "largely independent" of YAC. That is shown to be false above. The question is "Why would you make that claim?" the answer is "You are desperate to make Tannehill look average". To you, an average YPA = Average QB. It is inconvenient for a portion of the YPA to be attributable to something other than Tannehill. If I'm not mistaken, it has already been mentioned in one of these threads that the Dolphin receivers have lower than average YAC and that hurts your argument against Tannehill if you acknowledge that YPA is significantly affected by YAC.
2. YPA is a QB-only stat. This has also been refuted by me (once again using logic and the formulas used by the league to compute YPA). Here again, we have the same motivation for you. "Tannehill must be average". You ignored this post in the past, so I'll include it for your convenience:
Passing yards = yards in the air + yards after catch - sack yards.
Yards in the air is determined by the pass patterns called.
pass attempts are increased with no gain in passing yards if a receiver drops a pass
YPA = passing yards / pass attempts
All of the bolded items (IMO) are impacted by others more than the play of the QB. It is undeniable that they are at least affected by others.
So where am I wrong about YPA being a team stat? What is theoretical about any of this?