Zito's on a roll ... right?

After giving up just two runs in eight innings last night, Barry Zito has put together a nice little run, perhaps the second best in his three seasons with the Giants. My candidates for the five best six-start stretches since Zito signed his $126 million contract:

After that nice stretch late in '07, Zito started four more games in September and reverted to his usual unimpressive self, walking 10 and striking out 10 in 23 innings.

Is Zito doing anything different this year? Well, he's throwing more sliders and fewer curveballs, but then he did that last year, too. And the difference doesn't seem to be all that significant. According to Pitchf/x, last year 10 percent of his pitches were sliders and 16 percent were curves; this year it's 13 percent and 15 percent.

The simple truth, I think, is that Zito just doesn't throw as hard as he once did, which leads to fewer strikeouts, which leads to more hits, which leads to more runs. Among Zito's important underlying statistics, only his walk rate is significantly different from last season. But the anomaly is last season, not this season; his walk rate this season is right in line with his career numbers.

It's Zito's strikeout rate that's worth watching. As long as it hovers around six per nine innings -- as it has this year, and last year, and the year before -- he's not going to be the pitcher the Giants thought was worth $18 million per season. He'll quite likely finish this season with a better ERA than last season's 5.15. But his 4.53 mark in 2007 essentially reflected his true ability, and I haven't seen anything this year to make me think that ability has changed.