First of all, Shigetoshi Hasegawa has decided to hang 'em up after a nine year Major League career during which he won 45 games while posting a 3.71 ERA. He's still every bit the pitcher he was four years ago (his FIP's with Seattle have ranged from 3.72 to 4.06 over that span), but at 37 years old, he probably recognized that he wasn't about to get any better, so he thought it better to leave with dignity rather than be forced out by the competition. No word yet on whether Matt Thornton will issue a similar announcement.
Over at Baseball Musings, David Pinto offers up more evidence that the Mariners' defense wasn't really that good in 2005. Going beyond simple Defensive Efficiency, Pinto explored batted ball location data to find out how a team's defense should have performed, and then compared that figure to its DE(R). Although the Mariners finished with a better rating than expected, that was true of much of the league, and in the end they ranked 15th. This is similar to the analysis done in the Hardball Times Baseball Annual, in which the Mariners' defense ranked 18th. How much will they improve in 2006? Adding Yuniesky Betancourt for a full season will help, as will having Jose Lopez starting in place of Bret Boone, but Raul Ibanez's presence in left field will probably keep the team from making a significant improvement. Expect them to hover around the middle of the pack again next year, with an outside shot at finishing in the upper third.
On the same site, Pinto looks at which pitchers were most helped/hurt by their defenses, along with which pitchers produced batted balls that were the easiest/most difficult to field. As far as Mariner starters are concerned, only Jamie Moyer finished in the upper half of pitchers most helped by their defense. Joel Pineiro, Gil Meche, Aaron Sele, and Ryan Franklin finished 84th, 102nd, 109th, and 123rd, respectively, out of the 142 pitchers included in the study. Jarrod Washburn finished 45th.
It's the second table that I find to be more interesting, though. Franklin was actually the 7th-easiest pitcher to field behind last year, with a predicted Defensive Efficiency of .708 (based on the batted balls he allowed). Jarrod Washburn finished 83rd, suggesting that he's not actually a guy whose pitching style allows him to "beat" the DIPS system (which has been put forth as a popular theory since he signed). We don't know yet whether or not this metric has any predictive value, but it's fun to look at.
The last thing I want to point out is the awesome Fan Graphs website, which has recently been doing some real fascinating work. Like, for example, creating this chart showing the probably of a pitch in a certain location turning into a hit. If you scroll down, you can see similar charts for Albert Pujols and Vlad Guerrero, and they're frightening. Read the whole page and explore the rest of the site - it's fun stuff.