My older brother, who really should be co-authoring this blog (hint, hint, bro!), gave me the 2005 Bill James Handbook. Some of the information therein is duplicated online, but there's a fair amount of unique stuff, too, and on top of that, it's a handy reference that's all in one place. One of the nifty sections is a detailed listing of various park factors--measuring how much a particular ballpark affects offense.
Our lineup will feature several new faces, the most significant of which are Sexson and Beltre, but also include Jeremy Reed and, hopefully to some degree, Bucky Jacobsen. Is this offense built for Safeco Field?
First, the Handbook confirms the general belief that Safeco reduces run scoring across the board, but it is very favorable to left-handed power hitters. Specifically, from 2002-2004, Safeco was the worst hitters park, depressing run scoring by 12%. However, left-handed power hitters hit 13% more home runs in Safeco than in a league-average park (3rd place) while right-handers had a very hard time hitting home runs at Safeco, doing so at 86% of the league average clip (forth from the bottom). There is very little difference between the batting averages of right- and left-handed hitters at Safeco, so the disparity--lefthanders hit over 25% more home runs than righties--is really only signicant when it comes to home runs. It appears, though there is no more specific data in the Handbook, that those would-be right-handed HRs are mostly falling for hits, but staying inside the park.
At first glance, this is only good news for Reed, and bad news for Sexson and Beltre. Looking more closely at where Sexson hits his home runs (by looking at his mlb.com hit chart), he consistly hits for power to all fields, with a slight tendency to pull the ball more. Beltre's hit chart shows that 2004 was the first season he hit consistenly to all fields. Like Bret Boone, his success as a power hitter will largely depend on whether he can keep from trying to pull everything.
Safeco field does, for whatever reason, tend to increase walks, which is better news for Sexson than Beltre. Sexson has had an OBP 90-100 points higher than his batting average over the last several years (including last year's down year), while Beltre's OBP is only 50 points higher.
While it's hard to speculate how park factors will affect individual hitters, we should at least give context for each player as best we can. Beltre's old park, Dodger Stadium, also plays as a pitchers' park, albeit less severely. However, the left/right power disparity is reversed in L.A.: right-handed hitters hit home runs at 110% of the league average, while lefties did so at 98% of the average. Both the BOB in Arizona and Miller Park in Milwaukee are hitters park, neither favoring a particular side of the plate.
To sum it up: Any hitter is going to face a bit of an uphill battle at Safeco field, particuarly right-handed power hitters like Sexson. He should be able to maintain his high OBP, however. As for Betlre, there are even more reasons why his power could suffer at Safeco Field.
So what does the Handbook project?
Compare that to the top three full-time Mariners (below Ichiro) last year: