Wha? ... the fourth-out rule?

Chad Billingsley goes to the mound this afternoon for the Dodgers' home opener against the good-for-nothing Giants. I'm as excited as someone who resides 3,000 miles away can be.

But while the opener is less than four hours away, I'm still trying to wrap my head around how the Dodgers scored their first run in yesterday's game against the Diamondbacks. Have you ever heard of the fourth-out rule before yesterday? I hadn't. Neither had a bunch of people playing in Sunday's game.

Here is what happened. It is the top of the second inning with one out and Arizona leading 1-0.

Juan Pierre is on second base after hitting a one-out single and stealing second.

Andre Ethier is on third base after walking and advancing to third on Pierre's single.

Randy Wolf, a pretty good hitting pitcher, hits a line drive that Diamondbacks starter Dan Haren catches for the second out.

Haren throws to second baseman Felipe Lopez, to force out Juan Pierre, who was caught off second base, to complete the double play and get the third out.

But Diamondbacks second baseman Felipe Lopez, for some mystifying reason, does not touch second base to force out Pierre. Instead, Lopez skips right past the base and walks a few feet to tag out Pierre for the third out.

Meanwhile, Ethier was running on contact and crosses home plate before Pierre is tagged. The Diamondbacks run off the field after the third out, thinking the inning is over. But Dodgers bench coach Bob Schaefer spots the umpires huddling after the inning.

Schaefer talks to manager Joe Torre, who springs out of the dugout (well, as best as Torre can spring these days), to argue to the umpires that the run should count since Ethier crossed the plate before Pierre was tagged, and the Diamondbacks never appealed.

The umpires agree, and after some discussion with Diamondbacks manager Bob Melvin, Melvin agrees, too. (Melvin thought Lopez had touched second base).

It turns out that the Diamondbacks goofed twice on that play. The first goof (and in my mind the worst) was when Lopez failed to tag second and instead tagged Pierre. Like the Diamondbacks announcers said, you are always taught in baseball that when a potential out is in play, you get it the quickest way possible, which in this case would be tagging second.

The second mistake was the Diamondbacks leaving the field. They could have erased the Dodgers' run by appealing and throwing to Mark Reynolds at third base and retiring Ethier, who had left the base without tagging up. That would have been the FOURTH OUT of the inning, but it takes precedence over the third out that Lopez got because it saves a run from scoring.

This pretty much blew my mind yesterday. Apparently Schaefer had discussed the play in spring training and he had come across a similar situation way back in 1983. Torre was being credited for knowing the rule, but apparently it was his bench coach that knew the rule. That's why there are old guys sitting on the bench, people. You think they're doing nothing, but, oh, they are so doing something.

I don't pretend to know the rule completely (check out the play-by-play on baseball-reference.com. It's pretty interesting). But I do know that the guys on the field and in the dugout do need to know the rules. And blaming the rule book, saying it's a "stupid rule," is ridiculous. Blame the team that's been playing ball all their lives for not knowing it.

Anyway, the Dodgers scored a run on a double play and went on to win 3-1, winning the series against Arizona.

Yay, fourth-out rule!