Over the last four years, in all but one of which they’ve finished within three games of each other, the Yankees and the Boston Red Sox have played each other 82 times. These games have demonstrated, by their sheer, exhausting number, why baseball must return to the balanced schedule; they have also demonstrated that the two teams are nearly exact equals. (The Yankees lead, 42–40, though Boston is surely not hurting over the deficit, given their 2–0 advantage in world championships during this time.)

Between two teams matched so evenly, small margins make differences, so it was no surprise when Boston released longtime reserve catcher Doug Mirabelli yesterday. As he hit .196 in 107 games over the last two years, giving Mirabelli’s at bats to more or less anyone else represented an easy way to score more runs. As lousy a hitter as Mirabelli is, though, his likely replacement, Kevin Cash, is even worse. In 359 career at bats over five seasons, he’s batted .167 BA/.223 OBA/.265 SLG, which is about what Tom Glavine hits. What is Boston up to?

The seemingly minor move actually points up why the Red Sox have the edge in the American League East right now. This has less to do with talent than philosophy. Boston does have some peculiar quirks, like their absolute insistence on punting 150 at bats every year on a reserve catcher who can’t hit. These quirks generally, though, make sense within a larger framework. Mirabelli caught with Boston for so long not because he couldn’t hit, but because he could catch Tim Wakefield’s knuckleball. Cash will make the team, because the team is sure he can do so as well. Prioritizing knuckleball-catching in a reserve to the point where you’ll tolerate pitcher-level hitting makes a certain kind of sense. By contrast, the Yankees’ quirks, such as prioritizing glove work at first to the point where they’ve gone years without a first baseman who can hit, tend to make less sense. Their quirks are more like organizational neuroses.

Injuries to Boston pitching aces Josh Beckett and Curt Schilling have hooting New York fans awaiting the season with barely constrained glee, and they will obviously make a vastly greater difference this year than the question of whether Mirabelli or Cash catches Wakefield. They probably won’t make as big a difference as one might think, though, again because of philosophy.

The Yankees tend to make big, risky bets, like the decision to bank this year on rookie pitchers. It fits the structure of the team, which has always focused on running out the best star talent available and filling the gaps around the edges as needed. The top-level talent in the Bronx is, and has been for several years, a bit better than that in Boston. Problems come in at the edges, when the team ends up relying at times on the likes of Wil Nieves and Aaron Small.

Conversely, Boston tends to hedge its bets. Beckett, felled by a sore back, is expected to skip at least the Red Sox’s upcoming trip to Japan, where they’ll open the season. (Spending a day in a plane is good for no back, let alone a strained one.) Schilling will open the year on the 60-day disabled list and could conceivably miss the year. Still, even with both their World Series MVPs down, the team presents a credible rotation.

Daisuke Matsuzaka, who with improved consistency could win a Cy Young in his second year in America, is a perfectly respectable top starter. Wakefield, as usual, will be good for innings and the odd unhittable stretch. And while he’s a potential disaster in the making, Bartolo Colon could also be one of the year’s great bargains, and he is certainly worth taking a risk on as a reclamation project. Past those two, the Sox have lefty Jon Lester, 24, who might do a plausible Andy Pettitte impression for a few years if he can cut his walk rate by 10%, and Clay Buchholz, 23, who has a breaking pitch every bit as cartoonish as Joba Chamberlain’s, a fastball as good, and a major league no-hitter under his belt. Assuming minimal competence on Colon’s part, this rotation doesn’t stack up all that unfavorably to the Yankees’.

This is, again, not counting Beckett, arguably the best pitcher in the league, and Schilling, at this point a reasonable no. 4 starter. What would the Yankees’ rotation look like without Chien-Ming Wang and Mike Mussina? That Boston can boast this kind of depth is a testament to a relentless pursuit of advantages over a period of years: With two aces on the shelf, Boston can still throw out a heavily hyped Japanese import, a 15-year veteran of the team, two prospects, and an obese former Cy Young winner out to prove his shoulder is sound, and probably beat you. The Yankees have made their strides these last few years toward becoming a more complete and deeper team, but they haven’t caught Boston.

tmarchman@nysun.com