This is a particular pet peeve of mine. This isn't a knock against JJ, just against the way that stat is cited so much. Football isn't like baseball, where a pitcher directly controls ~50% of the outcome. (Side note: even most baseball stat guys will tell you W-L record is a really poor way to evaluate pitchers.) A QB has no control whatsoever over his defense and special teams, which make up over half the game. Then also subtract handoffs to RB's, and you're looking at maybe a third of the game a QB influences (though more so for Air Raid teams).

From what I remember ESPN started the whole QB W/L stat about 15 years ago for the NFL. They wanted something simple that fans could understand, since QB ratings are complicated. Looking at "QB W/L records," Dan Marino was a middling-to-below average QB. Also, Trent Dilfer was a very good one, as is Joe Flacco. BTW, ESPN later went to QBR.