Of course, there was the usual amount of bad Cubs gameplay, including Rich Hill getting thrown out at third to make the third out as he attempted to stretch an RBI double into a triple. On the other hand, Hill's a pitcher and you don't expect them to be able to run the bases well. You do expect them to show good judgment in where they're going to throw a ball that they've fielded, but that doesn't always happen, nor did it when Hill tried to get the lead runner at second and clonked him in the head instead. That miscue eventually cost the Cubs two runs in a game that they lost 5-3.
After Hill's basepath misadventure, it wasn't surprising that Angel Pagan stopped at second with a lead-off double, even though it looked like he'd be a cinch to make it to third. But the old baseball maxim is "Don't make the first or third out at third base" and we'd already seen the latter.
A few pitches later, the ball would make a short escape from Braves catcher Saltalamacchia, Pagan would attempt to advance, and he'd be thrown out at third to make the first out. Pagan and the third base coach started to argue and that was enough for Piniella.
He headed out to confront the third base umpire, tossed his cap, and was tossed himself. Dirt kicking, cap throwing, and cap kicking ensued, along with the bleachers unloading their cups and giveaway thermal mugs onto the field. Clean up and another Cubs loss followed.
In his press conference after the game, Piniella allowed that he'd seen the replay and that the ump had gotten the call right. He also announced that he'd now been ejected, so the sportswriters could stop writing about the fact that he hadn't been ejected yet.
Which may have been the whole objective of the argument...