Why the Red Sox shouldn't overreact

To take things a step further: Writers and radio talk-show hosts alike are starting to clamor for Theo Epstein to do something big this offseason because the Yankees are pulling away.

They're wrong.

In fact, it's pretty easy to demonstrate why the Red Sox already are vastly improved over the team they fielded on Opening Day last season -- a deal for Jason Bay or an adequate replacement notwithstanding.

Hold onto your hats: We're going to do this using the Wins Above Replacement statistic. The statistic itself is more complex than the NFL's quarterback rating, but here's the basic gist: It calculates how many runs a player produces at the plate and how many runs a player prevents in the field. You then compare this number to the number of runs an average player at that particular position would have produced and prevented.

Every 10 extra runs produced or prevented, people who are smarter than me have figured out, tends to turn into one extra win -- hence Wins Above Replacement. Voila.

The beauty of WAR is that it's cumulative. A guy who hits .300 and play 100 games is less valuable than a guy who hits .300 and plays 120 games. A relief pitcher with a 2.00 ERA in 70 innings is less valuable than a starting pitcher with a 4.00 ERA in 200 innings. (Really. We can go over it if you'd like.)

It's tough to quantify with other statistics just how significant it is that the Red Sox go from four months of Jason Varitek and two months of Victor Martinez to six months of Martinez. But because WAR is cumulative, we actually can add up four months of Varitek and two months of Martinez and add them together and compare them to six months of Martinez.

(This is, of course, all based on last season's numbers. But no one other than maybe Marco Scutaro seemed to have a career year and is due for a precipitous fall, and no one -- I'm looking at you, David Ortiz -- seems all that likely to have a huge bounce-back year that would skew the numbers dramatically.)

Catcher
2009, Varitek/Martinez: 2.4
(To do this, you have to take two-thirds of Varitek's 2009 WAR total and add it to one-third of Martinez's 2009 WAR total since he only played in Boston in August and September.)
2010, Martinez: 4.9

First base
Second base
Third base
All constants. If the Red Sox replace Mike Lowell with Adrian Beltre, that's an upgrade from 1.2 WAR to 2.4 WAR based mostly on the defense of the two respective players.

Shortstop
2009, Nick Green/Alex Gonzalez: 0.6
(The formula here is Green for four months plus Gonzalez for two months. This actually is even more generous than it appears because Julio Lugo managed a negative WAR in his tenure in Boston before he was designated for assignment.)
2010, Scutaro: 4.5

(Need another reminder why Scutaro is such an important pickup for the Red Sox? Even if he regresses to his numbers from two seasons ago, he's still at 2.7 and a two-win upgrade over the Green/Gonzalez duo of a year ago.)

Right field
Center field
Both constants.

Left field
2009, Jason Bay: 3.1
2010, Who knows?

Victor Martinez for an entire season in place of Victor Martinez for one-third of a season is a monster upgrade. Scutaro in place of Nick Green is another monster upgrade. That's the case -- and we can't emphasize this enough -- even if he regresses. Those two moves alone are worth at least five wins to the Red Sox.

If the Red Sox lose Bay, they'll need to make a move to replace him.

(It seems increasingly unlikely they'll lose Bay, by the way. The Angels have said they're out. The Mariners and their defense-first philosophy don't seem to be a fit. The Yankees always are lurking, but they've also made noise about keeping their payroll within reason. Who else is there? He ain't going back to Pittsburgh.)

If they do bring back Bay, there's no reason to go out and do something silly just because the Yankees made a trade for a center fielder.