I'm not sure where you're getting 100 AB at .250 OBP. Grossman has a .294 OBP in his last 100 or so at bats (i.e., since April 22), which is better than everyone on the team not named Castro or Miggy.
That said, Robbie's performance has been nothing short of horrific the last two weeks—like, nearly major league-worst horrific (arguably better than only ... wait for it ... Nick Castellanos!). So sure, let's move Robbie out of the top of the order and put someone else there. I'm fine with that. Please tell me who you think should be top of the order instead.
No matter whom you pick, you do know that Robbie can't come out of the lineup, right? Because of the why this team has been rostered, there is literally no one who can replace him outside of Eric Haase or Harold Castro—and either way, you still have Willi in left.
But yeah, let's blame Hinch for us being 14-28.