Ive been on the fence about it because of how many wrestlers still take L's, and the success of MMA fighters without wrestling backrounds still competing from Machida to Connor McGregor and Jose Aldo.
the ones that have always succeeded the most have been the ones who can pair their wrestling prowess with other aspects, especially these days. you can't come in and just be really good at ONE Martial Art anymore, doesn't matter if it's BJJ or Muay Thai or Wrestling or whatever. the guys who are the best have a super strong base in at least one MA but they have worked their ass off to get bloody good at the other aspects of the game.
the wrestlers who have had lots of success have built up their striking and they use their wrestling to hold the guy down & beat the shyt out of him. a lot of the best strikers have worked in their takedown defense so they can stay on their feet & impose their own game. some wrestling guys have worked hard on BJJ & use their wrestling to get their opp down & pressure them into making stupid mistakes where they can slip in a submission.
wrestling has always been the biggest aspect because it means you can control where you want to take the fight. wear him down, let him back up & smash on him to show off your strikes, take him down & submit him.
when Wrestlers don't do well it's because all they do is take someone down and lie on them. they don't try to ground & pound they don't know enough to go for submissions and the fight is boring because nothing happens.