I don't trust either but I trust Shorts less right now, I'd hold onto Tate unless something better is out there in waivers, prob a Steve Brown or Davante Adams, just based on upside. I'd trust Boldin more than Tate, the coaching staff change might make it worth-while to wait it out.
Shorts has been ruled out with a hammy injury. I would have gone with Tate anyway, but looks like your decision has been made for you (unless you want to play an inactive player, which I don't recommend ).