In terms of consistency and catalog of matches Rey is probably the best wrestler WWE has ever seen, so obviously yes he is underrated. He has perfected a structure underdog/FIP match that is almost flawless
But in terms of ratings and all that things that i don't really fucking care, things that i don't understand why everyone who isn't in the company should care, well he is where he should be. If he retire soon, he should be sended out with a bang
His stock has dropped a lot in the past two years but that's because he's barely on the show. He needs to come back regulary. He doesn't need a full time schedule anymore. Have him on Raw and Smackdown along with PPVs. He can put over guys like Barrett and Cesaro.
Rey is VERY underrated by internet fans and by people on this forum. I think its one of those things where we all know he is good and has done remarkable things but people like to give him a hard time just for the sake of ribbing someone. I think this is the case with him, Jeff Hardy, RVD and many others.