What is the strongest division in Major League Baseball in 2013?

I’ll admit it: I’m procrastinating again. But what of it?

So here’s what I’ve done. I took the game logs for the 2012 season and removed all intra-divisional matches. So out of the 2,430 games played last season, this left 1,358 games — all of them played between teams from different divisions.

Then I totaled up the collective wins for all teams within each division — again, excluding games played against each other — and came up with winning percentages for each of the six divisions. Here’s how it panned out:

AL West: 237-183 (.564)

AL East: 240-210 (.533)

NL East: 236-214 (.524)

NL West: 221-229 (.491)

NL Central: 225-271 (.454)

AL Central: 199-251 (.442)

I have yet to look into these figures on a historical continuum, but I’m guessing it’s a rarity for the AL East (traditionally thought of as the toughest division in baseball, at least for some time now) to be knocked off its perch at the top.

Anyone have a better way of measuring division strength? I’ve seen some articles written over the past few years that count all postseason series won (or even participated in) by teams from the various divisions. But since postseason success is partially determined by how a team performs within its own division, I’m not convinced that counting postseason series is the best way to measure division strength — especially given baseball’s disproportionately intra-division game schedules. Team performances against division rivals should be discounted from evaluations of overall division strength.

Unless I’m missing something?