Proper response to umpires is an essential component of survival as a baseball player. Some players go to lengths to learn names and details from umpires’ lives, then chat them up, as friends do, because it might buy some goodwill down the road.

Others have a more difficult time determining appropriate behavior.

That definition, of course, differs from ump to ump, and may even differ from day to day for the same guy, depending on his mood. Thursday in Pittsburgh, it appeared that plate umpire Angel Campos was a bit grumpy.

Things began in the second inning, with Matt Kemp—still upset over calls during his first-inning strikeout—chirping from the dugout toward the plate. As Andre Ethier stood in the batter’s box, Campos can be heard on the telecast saying toward the Dodgers dugout, “I don’t want to hear you again, I’m telling you that right now.” Somebody on the bench replies, “Just watch the game.”

“That’s all I’m telling you,” replies Campos.

“Just watch the game,” echoes the bench.

Talk from the dugout continued, though it can not be understood on the game audio, and a moment later Campos responded firmly, ejecting Kemp. (Watch it all here.)

According to Kemp, the phrase he used to break the Campos’ back: “Let’s go, Dre.” Manager Don Mattingly’s swift and outraged reaction to the ejection—he was tossed as well in short order—supports the statement.

“Matt got thrown out today for cheering for Andre,” Mattingly said after the game, as reported by MLB.com. “He was barking about the pitch to Dre, the second strike, but then Angel said, ‘That’s enough. I don’t want to hear another word.’ So the next thing that came out of [Matt’s mouth]—I heard it, clear as a bell—he said—because Matt knows where to stop—and Matt said, ‘Let’s go, Dre!’ And [Campos] looked over, and he threw him out of the game. It’s unacceptable.”

We’re left with the fact that an umpire has little reason to eject anyone over a statement of teammate support that can in no way be interpreted as an attack. We’re left with the fact that ejecting a team’s best player in the second inning of a game—especially a team in the heat of a pennant race—is an action that should only be utilized as a final resort, not a first one. We’re left with an outraged roster that, short its No. 3 hitter, ultimately fell to the Pirates, 10-6.

Something trumps all of that, however—a rule about which both Kemp and Mattingly should have been glaringly aware: Know Your Umps.

Campos clearly told them to zip it, and zip it they did not. Was it justified? Probably not. But to push things in such a manner when a directive has already been issued to refrain from said pushing isn’t the world’s greatest strategy. Kemp may feel like he backed down from a potential confrontation, but he clearly didn’t back down enough.

Umps don’t have to be just or reasonable or even correct. They’re hopefully held accountable for their actions at some point during or after the season, but in the moment, the wrongest-of-the-wrong umpires still has the power to toss a player for the smallest-of-the-small reasons. Kemp should never have given him that reason.

Pitcher Joe Blanton’s ejection in the fifth was another matter entirely. As the right-hander was heading for the dugout after being pulled from the game, he stared daggers at Campos until the umpire said something, then lit off toward him to engage in heated conversation. He knew what he was doing and he knew where it would end, and all went precisely according to plan. (Watch it here.)

Kemp: Not so much. His spot in the order came up three more times with runners on base—once with the bases loaded—and even though the Dodgers got a bunt single and a hit-by-pitch from his replacements to score runs in two of those situations, there’s little question that Kemp’s presence would have offered them significantly more.

The chance to win a game trumps nearly every one of baseball’s unwritten rules. When it comes to the one about knowing how to deal with umpires, however, the two go hand in hand. The Dodgers know this as well as anybody, but on Wednesday they ignored it—and it cost them.

Update (8/18): Mattingly, not Kemp, was suspended for his actions.