Unless Ronald Acuna Jr. has a knee joint that functions like a flamingo's — in other words, backwards from a human's — fully expect the superstar Atlanta Braves rookie to be out for the rest of the season. In fact, consider him likely to be unable to participate, except marginally, in 2019 Spring Training, and unlikely to return to Braves game action before midseason next year.
From all outward appearances, Acuna has ripped up his post-cruciate ligament, or alternately his ACL, which will require invasive surgery and disable him in much the manner that Chipper Jones and Danny Manning were disabled.
It's a sad state of affairs but the handwriting is on the wall and it looks like the Braves front office is being coy in not coming out with this forthwith.