Disagree. Those matches worked at the beginning because Brock had
1) An aura that Ryback never did. Even when was undefeated you never thought Ryback could break another wrestler in half if he really wanted to (shit, Ryback struggled with some feats of strength spots) nor create a sense of chaos like Brock
2) Brock's momentum towards those matches was pretty unique. He ended The Streak at Mania and then obliterated John Cena at Summerslam back to back. Then he wrecked havoc in the title match at the Rumble and then had that really special match with Reigns. That was what basically made WWE/Heyman think "suplex city" was the only way Lesnar could wrestle from that day forward. No fucking way a dude like Ryback would get in a position to not only be able to get that treatment but to have enough respect from the audience to make them work, even at 80% or whatever.