Ryback who has a podcast where he's talked about his WWE tme, and other things, says Taker criticized his gimmick. 

 Reeves stopped using his Ryback character in FCW after The Undertaker complained that the gimmick was "too 80s".  Dusty Rhodes told Reeves that he should adopt a comedic character instead of being his Ryback one. 

"I remember Undertaker came down to FCW and [Pat Buck was] here for this at this point. And CM Punk, actually, was there, with Taker. And I spent a bunch of money on, a got a new Ryback outfit made and I was all geeked up and jazzed up to, I had a promo cut on The Undertaker for Ryback and it was a weird thing having him just sitting there staring at you as you're in the ring cutting a promo on him. And you're like, 'who's this guy?' Do you know what I mean? But I just thought it was, I put my heart and soul into it. And I remember afterwards, I think Taker didn't approve of it or something. Yeah, I think that's what [Undetaker] said, that it was too 80s, which is funny looking back. Absolutely. And at that point, when you're in developmental, you just f--king get critiqued left and right. That's the name of the game and you just take it. And everything happened for a good reason and all that, but when you get a guy like The Undertaker saying something like that, changes have to be made.

So I get called into the office with Dusty Rhodes and he just tells me, he goes, 'I want you to do, you're a funny guy, we need to get away from this Ryback character.' And I'm [defeated]. Everything on my mind with the positivity and I created this, and we have something with this and 'you just love this - what are you talking about?', 'now you're being told you can't like this, but you told me you love this'. And he goes, 'I need you to come up with a new character.' And I go, 'can you help me out?' Like, he goes, 'all these stupid football players, like, they're hired with no experience.' He goes, 'you're not like that.' He goes, 'but I want you to make fun of it.' And he goes, 'you're a stupid former football player.'"

Can listen to it here