4 outs in an inning

Follow along closely here, because it gets complicated: The Dodgers
were trailing 1-0 with one out in the second inning when the perfect
storm of baseball weirdness happened.With runners on second and third base, the Dodgers' Randy Wolf hit a line drive back to Arizona pitcher Dan Haren, who turned and threw toward second base in order to complete what should have been an inning-ending double play.Had infielder Felipe Lopez just stepped on second base, he would have doubled off Juan Pierre and that would have been it. Three outs, end of inning. Instead, he ignored the bag, took a few more steps and tagged Pierre.Meanwhile, the runner on third base, the aforementioned Ethier, ran toward home on contact and
actually touched the plate a split-second before Pierre was tagged, which umpires noticed. Doesn’t matter. The Dodgers are out. Right? Wrong.
From the LA Times:
"When it happened, [coach] Bob Schaefer said, 'That's the four-out play.' "
— Dodgers manager Joe Torre The what?Because Lopez, the player with the ball, moved to tag a runner and not the base itself, he more or less put Pierre in a rundown, which extended the life of the play, giving the other baserunner time to score.If the D-backs had appealed to umpires that Ethier had left third base early — which he had — then umps would have ruled it the fourth out of the inning
and the run would have been taken off the board. The D-backs never
appealed because they didn't think they needed to. The defense just
left the field after Pierre was tagged, incorrectly thinking that the
inning was over without the run at home counting. Got it? "They did get it right,” Melvin said of the umpires. "That is the call: If you tag the
runner at second, you have to go to appeal before you come off the field to get
the runner at third."