Learning a lesson from Seattle

Theo Epstein completed his offseason overhaul of the Red Sox defense on Monday evening with the acquisition of Adrian Beltre, one of the elite defensive third basemen in the major leagues. In much the same way Mike Cameron arrived to replace Jason Bay, Beltre brings with him an iffy bat but a spectacular glove.

Like Cameron and shortstop Marco Scutaro, Beltre won't hit 30 home runs or drive in 100 runs -- but he will help turn Terry Francona's team into one of the American League's elite defensive units. The Red Sox will send seven above-average defensive players out into the field on a regular basis -- and that number doesn't even include Jacoby Ellsbury, a flashy center fielder who even critics have to concede has all the ability to become an elite defensive player.

Defense isn't as easy to measure as offense is.

One way to measure the impact of the overhaul, however, will be to look at the numbers compiled by the Red Sox pitching staff next season. The more ground balls that get scooped up and turned into outs, the better Josh Beckett, Jon Lester, John Lackey and Clay Buchholz are going to look.

For the uninitiated, batting average on balls in play (BABIP) is a key stat here. BABIP eliminates all plays in which the defense is not involved -- walks, strikeouts and home runs -- and comes up with just what it says it does: The hitter's batting average on balls put in play.

BABIP has a little bit to do with luck. Line drives sometimes find gloves, and line drives sometimes find grass. That's part of the game. A hitter isn't always going to get on base just because he made good contact -- and a pitcher isn't always going to get an out just because he made a good pitch. An average hitter has a BABIP of .300 over the course of a season, and an average pitcher therefore sees opponents compile a BABIP of .300 against him over the course of a season, too.

Defense, though, can affect BABIP. The more range a group of defenders has, the more line drives get caught -- and thus the lower the opponents' BABIP will be.

The Red Sox, widely considered one of the worst defensive teams in baseball last season, saw opponents compile a BABIP of .313 last season, second-highest in the major leagues.

The Seattle Mariners, widely considered one of the best defensive teams in baseball last season, saw opponents compile a BABIP of .274 last season, lowest in the major leagues.

What does that mean? It means that if opponents put the ball in play 4,000 times over the course of a season, the Mariners would allow 156 fewer base hits than the Red Sox would. That's almost a hit per game less -- and that hit per game has almost nothing to do with the quality of the pitcher on the mound.

(The assumuption is that luck evens out over 162 games.)

Let's dig a little deeper into the transformation Seattle made from below-average defensive team to elite defensive team, the same type of transition Epstein is trying to replicate with his team:

2008
UZR: minus-20.9, 20th in the major leagues

2009
UZR: 85.5, first in the major leagues

Here's how it translates to a pitching staff:

2008
Erik Bedard: 3.67 ERA (.272 BABIP)
Felix Hernandez: 3.45 ERA (.316 BABIP)
Jarrod Washburn: 4.69 ERA (.306 BABIP)
Team: 4.73 ERA (.309 BABIP)

2009
Erik Bedard: 2.82 ERA (.271 BABIP)
Felix Hernandez: 2.49 ERA (.280 BABIP)
Jarrod Washburn: 2.64 ERA (.245 BABIP)
Team: 3.87 ERA (.274 BABIP)

Seattle's team ERA ranked first in the American League even while its pitchers' strikeout-to-walk ratio -- the best indicator, normally, of pitching success -- ranked ninth in the American League, ahead only of Kansas City, Texas, Detroit, Baltimore and Cleveland.

Most importantly: While the Mariners actually saw their hitters' on-base percentage go down (from .318 in 2008 to .314 in 2009), they saw their win total go up (from 61 wins to 85 wins).

Maybe Seattle pitching coach Rick Adair possesses a genius that was untapped until last season.

Maybe it was the defense.

One more: Check out Lester's splits from last season:

First half (.333 BABIP): 3.87 ERA
Second half (.289 BABIP): 2.82 ERA

In the first half, Lester frequently pitched with Mike Lowell and Julio Lugo on the left side of the infield behind him. In the second half, Lester frequently pitched with Kevin Youkilis and Alex Gonzalez on the left side of the infield behind him.

Starting from Opening Day of next season, Lester will pitch with four Gold Glovers behind him: Youkilis at first base, Dustin Pedroia at second base, Beltre at third base and Cameron in either center field or left field. Scutaro and J.D. Drew aren't too shabby at shortstop and right field, either, and Jacoby Ellsbury has all the tools to be an elite center fielder.

Hernandez morphed from a promising young pitcher into a Cy Young contender almost overnight. His strikeout rate jumped and his walk rate dropped, and that played a big part in his success. So, too, though, did a BABIP of .280 -- the first sub-.300 BABIP he'd seen opponents compile since his rookie season.

If Lester can avoid the type of bad luck that cost him so much success in April and May a year ago, he might just win himself a Cy Young Award.

The same type of leap might await Buchholz, one of the American League's best ground-ball pitchers a year ago, and Beckett and Lackey, potentially dominant pitchers who rank in the top half of that same list.

No, the Red Sox might not score 900 runs the way they have three times since Epstein took over as general manager.

Scoring runs, though, is only half the battle.