That, in turn, prompted a childish tirade by Nationals general manager Mike Rizzo and a five-game suspension for Hamels.
Monday marked the first chance to see if any lasting repercussions remained and if the Nationals' rising dislike for the Phillies would be reciprocated at Citizens Bank Park.
We're sad to report that the series opener, won 2-1 by the Nationals, did not have the feel of an intense rivalry, but it did have the continuing frustration for a Phillies offense that is in the midst of earning a master's degree in the art of not scoring.
They have lost three straight and during that stretch they are 4 for 31 with runners in scoring position. The two hits in the last two games did not even provide a run.
The only thing really different about this night was that the crowd booed Harper every time he came to the plate in his first appearance at Citizens Bank Park. It was also a little odd that he came to the plate five times even though he only had four official plate appearances because one inning ended in the middle of his second at-bat.
So the kid had to endure one set of extra boos.
In the final analysis, Harper provided the winning run. He singled, stole his second career base and scored on an Ian Desmond single in the fourth off hard-luck loser Kyle Kendrick.
The Phillies botched several scoring chances, including one in the sixth off Gio Gonzalez when Placido Polanco failed to tag from third base on a Hunter Pence line drive that took center fielder Rick Ankiel to his knees. Polanco said it was a mistake.
"That's a tough line drive for everybody to read and I'm sure it was hard for him, too," Ankiel said. "I'm sure he was thinking it was a base hit, but I figured I was going to have to get up and hopefully have a shot at throwing him out."
Instead, Ankiel just had to stand up and softly return the ball to the infield.
Truth be told, there was more vitriol in the jeers directed at the Phillies in that bottom of the sixth inning when they placed runners at second and third with nobody out and still failed to score. There was nothing different, of course, about the crowds here being frustrated by the Phillies' lack of offense.
As for the Harper hatred, it seemed a little contrived. Despite a reputation for being overly cocky and immature during his rapid ascent through the Nationals' minor-league system, he has handled himself well so far at the big-league level.
When the Hamels' intentional bean-ball incident occurred, he handled it with remarkable aplomb, showing more maturity than both Hamels and Rizzo.
He continued to show class Monday night before singling twice, stealing a base and scoring the game-winning run in the Nationals' third win in four games against the Phillies this season.
Asked before the game about being hit by Hamels, Harper said it was not on his mind.
"Yeah, I'm not even thinking about that," he said. "This is a new series, a new day and I have a lot of respect for everybody in that other dugout. They have an All-Star team . . . guys who are All-Stars and who have been in this league for a long time. To come into this place and face Roy Halladay and Cliff Lee and Cole Hamels and all these guys . . . it's going to be a lot of fun."
Harper also showed some reverence toward the city and also displayed a keen sense of Philadelphia's sports history by naming some old-time stars. He named this city as one of the places he was most looking forward to play.
"Definitely, coming in here and playing the Phillies who have been a great team and coming into a place that has a lot of history and a great organization," Harper said. "You're playing in a place where Mike Schmidt and guys like that played. It's going to be a lot of fun in here. They have a great fan base and we're going to come in here and try to prove some people wrong.
"Philly has always had a great history in all their sports. . . . So it's going to be a lot of fun playing here. I'm excited to play in this town."
He was even more excited after the Nationals left the ballpark with a victory.
Contact Bob Brookover at email@example.com or @brookob on Twitter.