I wouldn't worry about them sitting Sanchez anytime soon. Coaching rule #1 no matter the sport.... If you've got a hot player, play him. Especially the pirates, it ain't like they're loaded with talent. Randa's just a stop gap vet that will give you decent but not great #s.
Nothing at all to worry about here. Freddy started all 27 games in May and 12 out of the 13 June games. He was definitely due for a rest today.
Reality is that Randa is the odd man out among the 4 players previously listed. None of the other three are going to sit regularly, although they may each get 1 day a week off. The good thing about it is that Freddy will go a long way to keeping his 3 position eligibility by playing all the positions!