PHILADELPHIA — Jerad Eickhoff made one mistake that equaled three others.

Eickhoff allowed four homers in Philadelphia’s 15-2 loss to the Pittsburgh Pirates on Thursday night.

Andrew McCutchen hit two solo homers, Jordy Mercer hit a three-run shot and John Jaso and Sean Rodriguez also went deep to help the Pirates split a four-game series.

“The first three home runs, I have no problems with those. Those happen. Solo home runs don’t hurt you,” Eickhoff said. “But the three-run home run, those just kill you. Those are frustrating. The biggest thing is I feel like I let the guys down in here. These guys are fighting. I have to live with that. That’s the most frustrating thing.”

Eickhoff (10-14) gave up six runs — three earned — and five hits in 6 2/3 innings.

“He made too many bad pitches,” manager Pete Mackanin said.

Chad Kuhl (4-3) pitched six effective innings in front of more than 100 family and friends from his nearby home state of Delaware. Kuhl (4-3) allowed two runs and four hits, striking out five. He retired the first 12 batters before Tommy Joseph lined a double to right-center in the fifth.

Jaso led off the game with his sixth homer. McCutchen drove one out to center in the fourth. Rodriguez connected in the fifth to make it 3-0.

Mercer’s shot increased the Pirates’ lead to 6-2 in the seventh.

“That can’t happen,” Eickhoff said. “With two guys on there and Mercer in the box, I’ve got to execute. That was a key point in the game. I think if I executed that pitch, it would have been a complete different ballgame.”

McCutchen hit his 23rd homer off Frank Herrmann in the eighth.

BUSTING OUT

The Pirates had seven hits and eight runs in the ninth to put the game way out of reach.

MINOR SHAKEUP

Dusty Wathan, who led Double-A Reading to the best record in the Eastern League this season and a second consecutive Eastern Division championship, will manage Philadelphia’s Triple-A affiliate, Lehigh Valley, in 2017. Wathan replaces Dave Brundage.

PROPER GOODBYE

Phillies manager Pete Mackanin plans to start Ryan Howard all three games of the season-ending home series vs. the Mets on Sept. 30-Oct. 2. The 2006 NL MVP is the last player remaining from Philadelphia’s 2008 World Series championship team. The Phillies will exercise a $10 million buyout after the season ends, so Howard is down to his final games in red pinstripes.

HEY A.J.

Former Pirates and Phillies pitcher A.J. Burnett drove from Maryland to Philadelphia to see two of his former teams. He watched the Pirates take batting practice on the field and chatted with many of his old teammates.

UP NEXT

Pirates: RHP Ryan Vogelsong (3-5, 4.66 ERA) starts the opener of a four-game series at Cincinnati. RHP Robert Stephenson (2-1, 4.43) goes for the Reds.

Phillies: LHP Adam Morgan (2-10, 5.73) takes the mound in the start of a three-game series vs. Miami. RHP Tom Koehler (9-11, 3.97) pitches for the Marlins.