Listen, pitchers have been hitting opposing batters forever, but there's almost always a reason. For instance, if a hitter stands at the plate and admires a home run, he's showing up the pitcher. Pitchers take exception to this.
"If I hit one of your 100-mph fastballs out of the park, I ought to be able to stand there and admire it," Barry Bonds once told Billy Wagner.
"You can do that, Barry," Wagner responded, "but you know what'll happen the next time?"
Wagner was telling Bonds that he would get his revenge with a fastball in the ribs. Whether he would have done it or not is another matter.
Sometimes pitchers hit batters to establish the inside part of the plate and remind hitters not to lean over the dish. Other times, pitchers throw low and inside to make hitters move their feet and snap them from their comfort zone.
But the overwhelming reason a pitcher hits a batter is to defend a teammate:
If the opposing pitcher hits one of our guys, our pitcher is going to hit one of theirs.
Rick Sutcliffe, then with the Orioles, once put the tying run on base in the bottom of the ninth inning in Anaheim after one of his teammates had been plunked.
Asked about it later, Sutcliffe said, "My guys are going to know I'm going to protect them."
Roger Clemens would understand. When a Boston hitter was hit in the first inning of a game at Fenway, then-Red Sox manager Kevin Kennedy went directly to Clemens and said, "Please don't retaliate."
Kennedy explained that his bullpen was in a fragile state, and that he badly needed seven or eight innings from his ace. Clemens nodded.
Between innings, Kennedy went to see plate umpire Tim McClelland, who had issued a warning, meaning that the next pitcher who hit someone would be ejected.
"Don't react, Tim," Kennedy told the ump. "Roger has promised me he's not going to hit anyone, but you know he'll still pitch inside."
Clemens went back to the mound and hit the first batter he faced. Later he told Kennedy, "I had no choice, skip."
Funny thing, McClelland didn't toss Clemens, and the matter was settled then and there.
Nolan Ryan would sometimes throw inside if he saw a hitter digging in the batter's box. Bob Gibson once hit a guy who'd bunted on him for the first hit of the game.
When I covered games at Comiskey Park in the 1980s, Don Drysdale would stick his head out of the broadcast booth and smile after an opposing batter hit a home run.
In his day, pitchers sometimes hit either the next hitter or the one who homered the next time he came up.
One night I sat in the Bard's Room at Comiskey and listened to Drysdale and Early Wynn discuss the best places to hit a batter. Wynn preferred the ribs, Drysdale the thigh.
If you didn't grow up in the game, if you're not of the game, these things may sound barbaric and, at times, dangerous.
Once, when Carlos Zambrano hit a couple of Cardinals early in a game at Wrigley Field, Tony La Russa ordered his pitcher not to respond.
Sammy Sosa stepped to the plate the next inning expecting the worst. When he wasn't hit, he flied out to right field, circled the mound and said to the pitcher, "Tell Tony, 'Thank you.'"
La Russa had decided that winning the game was more important than settling a score. He would settle up later. And he did.
La Russa appeared to have a simple philosophy. He would not allow an opposing pitcher to hit one of his guys without retribution.
Every pitcher knew that throwing at the Cardinals risked getting one of his own teammates hurt, and because they may have been less willing to hit a hitter, it might also have meant they were less willing to throw inside.
As crazy as all this sounds, it's the way the game has been played for 125 years. Craig Biggio once dressed down one of his teammates for not responding on a day when three Astros were plunked.
"Just take care of yourself," Biggio told the pitcher. "Don't pretend to give a rip about your teammates."
On the other hand, reliever Dan Wheeler's first appearance with the Astros after he'd been acquired from the Mets in 2004 was a galvanizing moment.
Wheeler walked in from the bullpen at Wrigley Field, plunked Derrek Lee as retaliation for Lance Berkman and Carlos Beltran being hit, and won huge respect in the clubhouse. Suddenly, a club that had been struggling to find its way went 26-7 and clinched a playoff berth on the final day of the regular season.
Still, virtually all of those pitches had a purpose. Maybe the purpose is gray to those of us who don't play the game, or haven't played the game. Inside the white lines, though, players understand.
Hamels appears not to have had a good reason for hitting Harper other than the fact that Harper is 19 years old and off to a great start. Baseball has so many unwritten rules that it's hard to keep 'em all straight. Hamels has written a new one.
Richard Justice is a columnist for MLB.com. Read his blog, Justice4U. This story was not subject to the approval of Major League Baseball or its clubs.