Though the Phillies have struggled to generate offense from the center-field position thus far this season, their shakeup in that spot Wednesday was due to personal, not performance, reasons.

Adam Haseley has decided to leave the team for personal reasons for an undetermined amount of time, making the way for Mickey Moniak -- the first overall pick in the 2016 Draft and the Phillies’ No. 12 prospect, per MLB Pipeline -- to return to the big leagues.

Moniak was recalled from Triple-A Lehigh Valley to assume Haseley’s active roster spot Wednesday. Haseley, who has a .190/.190/.238 slash through 21 plate appearances this season, has been placed on the restricted list.

Manager Joe Girardi said he was made aware of Haseley’s wishes on Wednesday but did not wish to elaborate on the reason.

“It’s personal reasons,” Girardi said. “We have no timetable, and we’re all thinking about Adam.”

Moniak expressed conflicting emotions about taking Haseley’s spot.

“Adam’s one of my closest friends in this organization,” he said. “I hope he’s OK, whatever it is. I’m going to reach out to him and make sure. You hate to see it. Whatever it may be, I hope that he’s all good.”

Moniak, who had a .214/.389/.214 slash in 18 plate appearances in his first exposure to the big leagues last season, will get opportunities against right-handed pitching.

“I think his plate discipline improved a lot,” Girardi said of Moniak. “I think his at-bats have improved a lot. … He’s going to get a shot, and we hope that he’s a boost in the arm.”

The Phillies could use one. They entered Wednesday with a .280 OPS from the center-field spot, worse than every team in baseball with the exception of the Pirates (.238). But while both Haseley and Roman Quinn were in a funk to start the season, Girardi said there was no plan to make a transaction on Wednesday prior to Haseley informing Girardi of his decision to leave the team.

Though performance at the alternate site can be tricky to evaluate, Girardi said the 22-year-old Moniak made a strong impression in Spring Training, where he had a .271/.368/.576 slash with two homers, six RBIs and seven walks.

“I hold myself to the highest of standards,” Moniak said. “I don’t think you can get too high or too low in this game. But the results I had in Spring Training definitely boosted my confidence and gave me a little more sense of belonging than I already had.”

In choosing Moniak for the promotion, the Phillies opted to leave veteran Odúbel Herrera, who was designated for assignment in January, at the alternate site and off the roster. Other options at the alternate site included Scott Kingery and Travis Jankowski. But Girardi expressed optimism that Moniak could seize the opportunity.

“I think he’s got a bright future,” Girardi said.

Bradley to miss three to four weeks
The oblique injury that landed reliever Archie Bradley on the injured list Sunday has been diagnosed as a Grade 1 strain, Girardi said. Bradley is expected to be ready to rejoin the Phillies in three to four weeks.

“He’s feeling better already, though,” Girardi said.

Bradley was replaced on the active roster by lefty JoJo Romero, who threw a scoreless inning in the first game of Tuesday’s doubleheader against the Mets.

“We’d love to have Archie back as soon as possible,” Girardi said, “but some guys have to step up a little, and I think they’re capable of doing that.”

Nola’s sinker use sinks
Aaron Nola was not his typically sharp self in back-to-back starts against the Mets, racking up high pitch counts that prevented him from going deep into those games. One culprit could be the reduction of his use of the sinker.

Last year, Nola threw it 20.7% of the time, with an average velocity of 91.7 mph. This year? Just 1.5%, with an 89.8-mph velocity.

“I think whenever you’re not using some of your best pitches because you don’t have a feel for them, you’re going to be different,” Girardi said. “So we have to help him get that feel back of that pitch, because a lot of times it can get you out of jams.”