Hector Neris, who began the season as the Philadelphia Phillies' closer, was optioned to Triple-A Lehigh Valley on Monday.
Neris lost his full-time closer job last month when he blew two saves in six days and showed inconsistency on the mound.
"We would like Hector to clear his head," Kapler said, according to Philly.com. "He just, quite frankly, needed a refresher."
His demotion comes a day after he nearly blew a five-run lead in the bottom of the ninth Sunday against the Milwaukee Brewers. With Philadelphia leading 10-5, Neris allowed a solo home run to Jesus Aguilar and a three-run shot to Eric Thames while recording just two outs. Jake Thompson came on to record the final out to earn his second save.
On Saturday, he had pitched a scoreless ninth to notch his 10th save on the season but first since May 21.
For the season, Neris is 1-3 with a 6.00 ERA and the 10 saves in 13 opportunities. He had 26 saves in 2017.