The reported injury for Rey Mysterio is said to be legitimate and not a kayfabe storyline by WWE.
Rey Mysterio was announced to face Seth Rollins at RAW earlier this week. However, WWE announced that Rey had suffered a torn triceps during the tag team match at Payback. He was replaced in the match by his Dominik. Rey did appear on RAW but only in a backstage segment and was covering his hand with a sleeve.
At first, it was thought as another bait and switch tactic from WWE to replace Rey with Dominik. However, Dave Meltzer came out with the report that the injury to Rey is legitimate and it actually happened at Payback itself.
The tear is not considered as serious as a full tear and will not require surgery. Rey will reportedly be able to recover through rehabilitation process. He is expected to return in two months or even less time.
Rey has earlier been written off from storylines with kayfabe eye injuries during his feud with Seth Rollins. Back in May, Rollins damaged his eye socket which led to Mysterio taking one month off from in-ring action. Rey once again did not appear for a couple of weeks on RAW after Seth Rollins defeated him “Eye for an Eye” match at Extreme Rules.