One of the things Jets fans like to take regarding Sanchez is the "He was better before/when" approach. Having tired of reading that over and over, I decided to look at his individual games. Here's the reality, as broken down by QB rating:
Rookie year:
100+ - 3 times
90 to 100 - 1 time
70 to 90 - 5 times
Below 70 - 6 times
Second year
100+ - 4 times
90 to 100 - 0 times
70 to 90 - 5 times
Below 70 - 6 times
Third year
100+ - 2 times
90 to 100 - 4 times
70 to 90 - 4 times
Below 70 - 6 times
This year, so far
100+ - 1 time
90 to 100 - 0 times
70 to 90 - 0 times
Below 70 - 3 times
Sanchez has been remarkably consistent in his inconsistency, and he's very rarely shown excellence. In each of his 3 full seasons, he's tossed in 6 games where his QB rating was below 70, and he's only gone over 100 nine times (3 times per year, on average).
So, when you look at the numbers on a game-by-game basis, you see that Sanchez wasn't clearly better year 1, or year 2, or year 3. He's simply been the same stiff, year after year, and he's basically giving the Jets 6 games a year where they should lose based solely upon QB play. The most significant difference, such as it is, is simply that his biggest "suck" games were worse as a rookie than they have been since (He had one game with an 8.3 rating for example), and that should come as no surprise to anyone.
In contrast, Brady's been below 70 just 4 times in that same period, 3 of those 4 times came in his first year back from the ACL injury (2009) and the only other time Brady was below 70 was when he had a 69.5 in the 2010 game against the Ravens. He's had 32 games with a QB rating above 100 in that same stretch of time.
Despite the insistence of a large portion of Jets fans, the suck of that franchise, in terms of on-the-field-play, starts with the QB.