Some quick information based on a few hours' worth of research...
Through three Major League starts, Fister has thrown 275 pitches and missed 25 bats, for a swinging strike rate of 9.1%.
As a starter in Tacoma, Fister threw 1474 pitches and missed 91 bats, for a swinging strike rate of 6.2%.
Seem strange? It should - pitchers usually don't get promoted to face the best competition in the world and suddenly get better. You'd expect them to get worse, and, indeed, that's what the numbers show. After spending a while on StatCorner looking at guys who've started this year, here's what I found:
-46 guys who've started this year have recently had a season in which they threw at least 700 pitches as a starter in both AAA and the bigs. Their average SwS% in AAA was 9.7%, against 7.5% in the Majors. Only five of them saw their rates improve, with 11% being the biggest improvement. (Ubaldo Jimenez, 2007)
-96 guys who've started this year have recently had a season in which they threw at least 500 pitches as a starter in both AAA and the bigs. Their average SwS% in AAA was 9.6%, against 7.4% in the Majors. Only ten of them saw their rates improve, with 29% being the biggest improvement. (Dustin Nippert, 2008)
-147 guys who've started this year have recently had a season in which they threw at least 300 pitches as a starter in both AAA and the bigs. Their average SwS% in AAA was 9.7%, against 7.4% in the Majors. Only 18 of them saw their rates improve, with 58% being the biggest improvement. (Jo-Jo Reyes 2009)
-64 guys who've started this year have recently had a season in which they debuted* in the Majors while throwing at least 300 pitches in both AAA and the bigs. Their average SwS% in AAA was 9.9%, against 7.4% in the Majors. Only eight of them saw their rates improve, with 26% being the biggest improvement. (Craig Stammen, 2009)
* debut = had never before thrown 300 pitches in the Majors
It's worth noting that a lot of the guys who had the biggest improvements had previously shown a better ability to miss bats in AAA, or a worse ability to miss bats in the bigs. Stammen, for example, went from 4.6% to 5.8% this year upon getting promoted, but he was at 10.1% in AAA a year ago. The same kind of thing goes for a lot of the others, with Josh Geer being one of the only exceptions. Fister, of course, has never been known as a strikeout machine.
Coming to the Majors and having your swinging strike rate improve is clearly unusual, happening to just 1/8 of the debuter pool and about 1/8 of the overall pool. And it's not like Fister has gone from 6.2% to something like 6.8%; he's gone from 6.2% all the way up to 9.1%, an increase of nearly 50%. It's a very small sample, but swinging strike rate tends to stabilize quickly, and Fister has missed bats at about twice the rate we would've expected.
What do we make of this? I wish I could tell you, but unfortunately this post is more about asking questions than offering solutions. I don't know why Fister has been able to be so confounding with Seattle so far. But though he's only made three starts, the numbers are right there, and they're extremely encouraging. Even if and when Fister regresses from his current rate of missed bats, there's reason to believe that he's not just another Carlos Silva in that department, and with his ability to hit his location and throw strikes (69% today with a few missed calls), we really may have something here. I didn't care about Fister when he first got the call, but he's done nothing but impress since arriving on the scene, and I'm starting to believe. Doug Fister: not just some guy anymore. Now he's some guy with promise.
(Also, we lost! Here's a chart. Go enjoy your Saturday.)