I do not think he believes that Brady was the 17th best QB last season. I do not see where you draw that conclusion from his argument.
I think the poster believes that thus far in his career, Ryan Tannehill has been nothing more than mediocre, and some posters on here reach and spin information to suggest he is much more than that. The facts indeed support his claim.
In the beginning I'm sure that when the first person claimed his favorite batter was the best in the league and used stats to back that claim up he met resistance, very similar resistance we're seeing to accepting the passer rating stat as a measure of the QB. "But he's playing a different team." "He didn't play the same pitcher." "He always has guys on the base." "The weather is different" "The dimensions of the field are different."
But over time after it became painfully obvious that the best hitters were almost always near the top of the rankings it just became commonly accepted that batting average is a very good indicator of a hitters abilities. Simple logic tests can prove this is the case. Do the best hitters tend to have the best batting average? And does it work in reverse-- Do the best batting averages tend to include the best hitters? If the answer to both is yes and the same players tend to show up on both lists then logically batting average is a good indicator of a batters ability, regardless of any extenuating circumstances. But we already knew that.
So using the same logic test:
I think everybody would agree that known great QBs are Peyton Manning, Aaron Rodgers, Tom Brady and Drew Brees
These players all have multiple 100+ passer rating seasons, so what separates top QBs is they tend to have multiple 100+ seasons
Is the reverse true? Here is a list of all QBs in the history of the league with multiple 100+ seasons:
Aaron Rodgers
Joe Montana
Peyton Manning
Tom Brady
Steve Young
Drew Brees
Kurt Warner
Ben Roethlisberger
Phillip Rivers
Russell Wilson
Looks like a list of great QBs to me. So how can anybody reasonably deny that passer rating correlates with QB play? It passes a very simple logic test: the best QBs typically have the best ratings and the best ratings are typically just a list of the best QBs.
And as far as Brady being rated 17, interpreting stats is an art as much as a science. For me passer rating for a season is more of a pass/fail test than a ranking.
100 and above =exceptional
87-100 =very good
70-87=average
below 70=poor
You can nitpick on where to draw the lines and that could even be fluid over years or circumstances but I'll say it until I'm blue in the face: a 100+ rating over a season is indicative of great QB'ing.