Rakuten Eagles' president Yozo Tachibana spoke to the media today and announced that Senichi Hoshino will not be able to manage the Pacific League during the upcoming All-Star Series. He cited health issues as a reason.
Tachibana spoke to Hoshino over the phone in the morning and both sides decided it would be best for him to step down. The NPB has already been notified.
"[Hoshino] tried his best to prepare himself for the All-Star Series, but he is still not ready. We told the NPB he had to step down. I am very sorry that this decision had to come just a week before [the series]," Tachibana said.
Source: Nikkan Sports 7/12/2014