You may not be a machine Joe, but that doesn't mean we can't treat you like one.
The result was bad - a loss to the White Sox that leaves the Twins currently 4.5 games back of the Tigers. But the implication might have been worse.
Joe Nathan hasn't been right, and it's been apparent for several weeks, starting with a blown save that led to a 53 pitch outing against the Royals on August 21st. Nathan has been a stable and nearly unstoppable force since his arrival in 2004 in the AJ Pierzynski trade. This year and last you can change that article to "the", as in "the" stable and nearly unstoppable force. Because there hasn't been much else. Losing him might be the final blow to a team that has been deflecting a lot of final blows this season.
You can probably go somewhere else on the Twins blogosphere for a breakdown of Nathan's mechanics, but when I want to figure out if there's something wrong with a pitcher, I treat them like a machine. And the red indicator light for a pitcher with a serious problem is a sharp decline in his strikeout rate. So let's use that nifty Excel Chart Wizard and map Nathan's K/9 rate for each month since he got here, and compare it to his average rate over that time:
Nathan's strikeout rate this year and last has generally been a little lower than his overall average. That's to be expected, by the way - it happens to pitchers in the major leagues as hitters slowly adjust. But in Nathan's case, his strikeout rate has been increasing towards the end of this year, and was as high in August as it has been for the last couple years. That's far from a blinking red indicator light.
Is he trying to strike out people too much? Is he nibbling? It can't hurt to take a look and see if his control is off a bit, can it? Let's take a look at his BB/9 (walks per nine innings) rate over the same period.
Remember, on this chart, a peak is bad, and valleys are good. And last month, Nathan was at a peak that he hadn't seen since September of 2007 , when he blew back-to-back saves. Before that he reached this level back in September of 2006, when he was actually very, very good, because he was striking out a ton of people to make up for the walks.
But if you've been watching Nathan, the revelation that he's struggling with his control isn't a revelation at all. He's been missing the target on the outside of the plate consistently, especially against left-handed hitters. That's not exactly good news, but it isn't as bad as it could be. The machine definitely needs a tune-up, but he doesn't need an overhaul.