It is hard to call the M's signing of Carlos Silva controversial, but at the same time few would argue that they overpaid for him. He has been a solid, durable starter throughout his career, and that simply is not worth $12 million a year. However, the argument was that Silva's stuff translates much better in Safeco Field than it did in his old home park, the Metrodome. The Metrodome is known to have a fast service, so between natural grass, a great infield defense, and the steady diet of ground balls that Silva's sinker produces, the thought was that Silva would be much better than average in Seattle. The argument makes some sense.
However, the statistics simply did not back up the Mariners' claims. First of all, though Silva's primary pitch is a sinker, he is not quite a ground ball specialist. For his career, his ground ball to fly ball ratio is 1.58, and the average ratio is somewhere around 1.3. So, Silva does induce more ground balls than the average pitcher, but he is not among the elite sinker-ballers (for instance, Brandon Webb's career GB/FB ratio is a ridiculous 3.21, and Roy Halladay's is 1.99). Furthermore, Silva's numbers in the Metrodome were actually considerably better than his road numbers last year, so to argue that the Metrodome hurt him is comical. Statistically, there was no good reason to expect Carlos Silva to improve noticeably by pitching more in Safeco Field.
Still, to this point, the Mariners have looked like they are right. Just last night Silva shut down the A's, and for the season he is 3-0 with a 2.79 ERA, all while averaging over 7 innings a start. In fact, Silva's 2008 performance thus far equates to an 82 in my rating system, when last year he was a 75. So, will Silva continue to pitch like this?
I would not bet on it. Even with only four starts' worth of a sampling size, Silva's ground ball to fly ball ratio, strikeout, and walk rates are all comparable to his career averages. In other words, all of these numbers indicate Silva is probably roughly the same pitcher he has always been. However, he is giving up an average of about two fewer hits per every nine innings pitched. That may not sound like much, but it is roughly the difference between a 1.15 WHIP and a 1.35 WHIP, or roughly 35-40 points in on-base percentage. Perhaps playing in Safeco behind a good infield defense accounts for some of the improvement, but it is highly unlikely that it accounts for all of it. More likely, the ball is finding gloves for Carlos Silva right now, and he is a bit lucky. Especially as the weather warms up, I expect Carlos Silva to start giving up more hits, and subsequently more runs. He will still be a solid pitcher, but enjoy the great start while it lasts.