I think everyone is leaning too heavy on Machida's fancy KOs and ignoring his many recent uneventful wins/losses.
Mousasi/Machida was nothing to write home about, he had some good flurries, but nothing to be scared of. Machida couldn't get his striking going against Davis and lost. He had a split win against Hendo. He got tangled up and submitted by an elite wrestler in Jones.
Weidman has better wrestling than Davis (I'M NOT SAYING HE'S BETTER- but his wrestling is more on par with Jones). He has the length of a LHW. His submission game, including his standing guillotine, is very similar to Jones. Plus, he's very well coached and won't make dumb mistakes, which a lot of his opponents seem to make. Plus, he is no slouch in the striking department, using his distance and timing better than most.
I'm not writing Machida off, but people are forgetting Machida isn't invincible. He has been KOd, submitted, decisioned, out grappled and out wrestled- Weidman hasn't.