Once upon a time, in a different era of baseball, pitchers thought nothing of throwing at hitters’ heads. That’s changed.

In a different era of baseball, pitchers would drill a guy not only for his own success, but for the success of his teammates. The player in front of you hits a homer? Expect to wear one. That, too, has changed.

Both of those developments are unequivocally for the better.

But then we have something like last night, when four members of the Washington Nationals went deep in the span of five batters—four of them in a row—during a single inning, part of an eight-homer day. It was a ridiculous show of firepower, and the Milwaukee Brewers didn’t do a thing to slow it down.

Before proceeding, I offer a snippet from an interview with former Brewers pitcher and current Phillies hitting coach Bob McClure, conducted years ago for The Baseball Codes:

We were in Yankee Stadium one time, and I gave up back-to-back home runs to two left-handers. I’d given up back-to-back home runs before, but not to two lefties. Dave Kingman was up next. [Catcher] Charlie Moore called for a fastball away. He knew better, anyway. He was just going through them all. Fastball away. No. Curveball. No. Changeup. No. Fastball in. No. And then he goes [McClure flicks his thumb from out of his fist, under his index finger, the universal symbol for knock him down]. So I threw it, and it was a good one—it went right underneath him and almost flipped him. He hit the dirt and was all dusty. His helmet was off. He grabbed his bat and his helmet and gets right back in there. I threw him a changeup and he popped up to first base.

The upshot, from McClure: “Back then, we were taught the 0-2 up and in. Home run, next guy: boom! Knock him down.”

McClure was not trying to hit Kingman, or to hurt him. He was trying to disrupt his comfort in the batter’s box. Be clear about that distinction, because it could have done Brewers pitcher Michael Blazek—who gave up every one of Washington’s fifth-inning homers yesterday—a bit of good. The Nationals were clearly relaxed in the batter’s box. Utilizing inside pitches—not to hit anyone, but to move their feet, back them off the plate and make them consider the possibilities—could have disrupted that comfort. It did not appear to have any place in Milwaukee’s game plan, and the assault continued.

Historically, the most glaring example of this type of thing came from Paul Foytack, the first of the four pitchers (including Blazek) ever to give up four straight homers. While with the Los Angeles Angels in 1963, against Cleveland, Foytack surrendered three straight—to Woodie Held, pitcher Pedro Ramos (batting a robust .109 at the time) and Tito Francona—and set out to knock down the next batter, rookie Larry Brown. Even that didn’t go quite as planned, as Brown ended up hitting his first career home run. “That shows you what kind of control I had,” Foytack told reporters later.

The modern game, however, has eschewed inside pitching to such a degree that the idea never appeared to cross Blazek’s mind, nor—given that it was the pitcher’s first-ever big league start—that of his manager, Craig Counsell. What we’re left with is a record-tying performance that Blazek would rather have no part of.

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Those four homers gave us another example of the evolution of the unwritten rules, which had more to do with the hitters than with Blazek. A generation ago, the code dictated that a batter would take the first pitch following back-to-back home runs. It was a courtesy offered a struggling opponent.

Take it from three-time All-Star Hal McRae: “Someone would pull you to the side and say, ‘Look, there have been two consecutive home runs hit. The third batter doesn’t swing at the first pitch.’ Take the first pitch. Alert the pitcher that you’re not swinging, that you know he’s out there, you respect him and you respect the job that he’s trying to do. So you take the first pitch, saying, ‘I’m not going to try to come up here and try to hit the third consecutive home run.’ After the first pitch, it’s okay for you to do your job.”

Yesterday, Blazek’s first pitches to Wilmer Difo and Bryce Harper—the second and third of the quartet of consecutive-homer hitters—were out of the strike zone, and taken. His first pitch to the fourth member of that group, Ryan Zimmerman, was down the pipe, and blasted over the left-center field fence.

The interesting part of this is not that the Nationals didn’t observe an obscure unwritten rule, but the extreme probability that nobody in their clubhouse apart from manager Dusty Baker and perhaps a coach or two has even heard of it. The idea of sacrificing statistics for a bit of kindness to an opponent is so beyond the pale in the modern game (and, frankly, has been that way since the 1980s), that it’s almost beyond comprehension.

It does serve, however, as a marker for how far the game has come, and the extreme evolution of its moral compass.