Daisuke Matsuzaka was scratched from last night's game due to rain. He's scheduled to pitch against Sidney Ponson this afternoon. With an 18-2 record and a 2.80 ERA, you might be under the impression that Matsuzaka was having a monumental year. The reality though is that he's had a monumentally lucky year.
For starters, he's walking more than five batters per nine innings. That's a huge amount (more than Brian Bruney) - it's the second highest walk rate among pitchers with at least 150 innings (only trailing the infamous Barry Zito), and it's up from 3.5 in 2007. In addition, he's striking out fewer batters (8.2 vs. 8.8 last year) with the exact same groundball, flyball, line drive and WHIP rates. You've got to be extremely lucky to increase your walk rate, decrease your strikeout rate, maintain most of your other peripherals and still have a winning record and good ERA.
The big differences are his lowered home run rate and BABIP (batting average on balls in play). Since hitters are still hitting the balls just as hard as last year (indicated by his identical line drive rate), it leads me to believe that his lowered HR rate is also due to luck. And BABIP notoriously fluctuates for pitchers from year to year. Even in Japan, where he was the premier hurler, his BABIP averaged ~.283. This year, it's just .266 compared to .306 last year.
His FIP (Fielding Independent Pitching) ERA of 4.00 tells the true story. It means that he's lucky and playing behind a good defense that converts a lot of those line drives into outs. Last year his ERA (4.40) and record (15-12) were far truer to his FIP (4.23) for that of an above average pitcher.
So is Daisuke worth ~$20 million a year? Hell no.