There's been some talk about how the Niners have been on a quarterback roller coaster with Alex Smith. 1 week Smith is challenging records for completion percentage, 1 week he's throwing 3 interceptions in a single game. But I don't think a roller coaster is the appropriate analogy. What we have is more of a Dr. Jeckyll and Mr. Hyde situation. In 4 of the 8 games (@GB, Det, Buf, @Ari) we've enjoyed elite performances from Alex. In those games his stats are remarkable
76/100 969 yds 9.69 ypc 10 tds 0 ints 139 rating
extrapolate that across a season and you have a 40 tds, 0 ints and nearly 3900 yds. Its safe to say that, that level of production and efficiency is impossible to sustain. And of course every qb has some bad games but look at Smiths other four starts:
69/109 687 yds 6.30 ypc 2 tds 5 ints 68 rating
I won't bother to extrapolate that across a season but safe to say that few qbs have had such a bad hypothetical season for the simple reason that they'd be benched before they made it 16 games. Breaking it down, Smith has 4 games over 100 rating and 4 games of ~80 or less rating. There's nothing inbetween! Going back to the rollercoaster analogy if Smith was an amusement park ride the train would derail sometime between week 5 and 6 if not sooner.
One obvious question is what is causing this. Its not home vs away since 2 of Smith's great games were on the road and his 2 worst were at home. Its not September v October. 1 possible explanation is grass v turf. On grass Smith has a 110 rating and on turf he has an 80. Is it that the game speeds up too much for him? I don't know if I buy this as 2 of his worst games were at Candlestick's slow surface. Theres also an interesting break on the direction of pass plays. To the right he has a rating of 50 and in all other directions he's better than 95. What's up with that?
A more obvious explanation would be that he does poorly against better defenses. Thats only natural but that argument doesn't completely fit the data. By pass rating the Jets and Hawks are the 2 toughest defenses he's faced and those were "bad games". However, the Cards and Packers are the next 2 toughest pass defenses he's faced and he scorched both of them. His worst game by far was against the Giants and they're the 5th toughest team he's faced by this metric.
It would take more research than I'm willing to do to prove that this level of variability is unprecedented but lets compare him to a few of his peers in 2012. I'm grading based on pass rating which is admittedly imperfect but easy to look up. (100+ great, 85-100 good, 70-85 below average, 70- bad)
Peyton Manning- 6 great games, 1 below average, 1 bad
Aaron Rodgers- 4 great, 3 good, 2 below average
Matt Ryan- 6 great, 1 good, 1 bad
Alex Smith- 4 great, 3 below average, 1 bad
Big Ben- 3 great, 3 good, 2 below average
Tom Brady- 5 great, 1 good, 2 below average
Matt Schaub- 5 great, 1 good, 1 below average, 1 bad
Drew Brees- 4 great, 1 good, 3 below average
Josh Freeman- 4 great, 1 good, 2 below average, 1 bad
Bob Griffin- 3 great, 2 good, 3 below average
Oddly only Peyton and Alex have played every game outside of the 85-100 level. Making Smith's performance even stranger, his 2 peak performances have been all but perfect. Its also worth pointing out that in Smith's "great games" the niners are 4-0 and in his other 4 starts they're 2-2. Hopefully we see more "woo-hoo" than "'doh" in the second half but I'd be satisfied if we just got 8 games above average play.