Supposedly there is. I don't think anyone's gone so far as to really figure it out but the safe bet is to get veterans and prospects a few games' worth of at-bats or innings just in case, unless you've got a low-Health player and would rather chance a slight decline than an injury. It would be a task to determine whether the occasional decline of a 32-yo who sat out ST was caused by not playing or was going to happen anyway.