Well I don't believe they are as inconsistent as the year to year variation indicates. I believe the year to year variation is, in large part, caused by changes in the team around them. That belief is consistent with the opinions of professional coverage of the sport. Brady's drop off this season is a direct result of depleted/new receiving corp. That opinion is shared by every report that covered the situation in NE this season.
That can sure be true, but if it's objectively supported that such variation occurs within a significantly higher YPA range for good QBs than for not-so-good QBs, why would that shift the primary focus off of the QB? Why wouldn't the emphasis continue to be on the player (the QB) who enables the team to function within a significantly higher YPA range regardless of variation in other variables?
In other words, your stellar supporting cast isn't getting Chad Henne anywhere, whereas Tom Brady may very well turn chicken **** into chicken salad.
If the roles of other players have a great deal to do with the functioning of the QB, how can their play have no significant effect on the QBs measured performance?
Their functioning
can have a significant effect on the QB's measurable performance,
in theory. If objective evidence of that were presented to me, I'd sure give it every bit of thoughtful consideration I do other high-quality information.
Of course it's also plausible that
the QB has more of a measurable effect on
those other players' performance. This thing doesn't just work in one direction in theory.
If the other players on offense were as insignificant as you described, it would make no sense to draft players at those positions high in the draft or pay them highly. Why not lineup a group of undrafted free agents on the OL?
I'm afraid my position on this is getting more and more caricatured as the discussion progresses. The position is that having a good QB is necessary for high-level competitiveness in the vast majority of cases. Obviously, however, that doesn't mean one can march a QB out onto the field alone and have him go up against 11 opposing players.
Once a team has an adequate QB, it can then turn its attention to the remainder of the roster, and it might as well do that with its draft picks, regardless of how high they are, given that those players aren't paid all that much, comparatively speaking, during their initial contract.
Now, who gets paid big, again, is starting to evolve toward the players who revolve around the passing game on both sides of the ball, which again has a great deal to do with "quarterbacking." If other teams have a Peyton Manning or an Aaron Rodgers, you can't expect to be highly competitive with them unless you can defend against the effect that player has on his team's likelihood of winning, which is great, and which is why DEs and DBs are typically your high-dollar players on defense.
By the same token, support players on offense (WR, TE, LT) can facilitate the effectiveness of an adequate QB, which gets them paid big as well, but a team would be far less likely to be highly competitive, even
with those high-dollar surrounding players on offense and defense, in the absence of an adequate QB.