I am not shy about criticizing the Twins on player evaluation but I think it’s really a stretch to say they blew it with Hendricks. He got passed around to several teams due to ineffectiveness after the Twins let him go. Finally he starts throwing substantially harder and becomes a good reliever. It’s interesting because he was kind of a slightly built guy with the Twins - when he had success he was built like a linebacker so he must have really hit those, ahem, weights.
As far as Varland goes I hope he succeeds but the jury is still out on him even in relief. He has the velocity but his fastball is pretty straight. He has no effective secondary pitches with the possible exception of a baby cutter. If he can really spot those two pitches he could be a good reliever but the margin for error is pretty slim.