Like various other people who've become well known through the use of social media, Zack Ryder was essentially just a little bit of a passing fad. We've all heard/seen people who've gotten their 15 minutes of fame due to posting something on YouTube, Twitter, Facebook or whatever and Ryder is basically in the same boat.
Interest in Zack Ryder started fading almost the minute his push started. People thought it was a fun moment when he interacted with Hugh Jackman on Raw a few years back and I agree, it was fun and Jackman seemed to genuinely enjoy himself out there. Jackman "helping" Ryder score a win over Dolph Ziggler was fun and seeing him win the US title from Ziggler at TLC in 2011 was also fun. However, once Ziggler got there, people did start to lose interest due in part to Ryder's character. Ryder was a quirky, more family friendly version of a Jersey Shore party boy, which was okay but it became a hindrance when he had to get into real feuds. It's difficult to take a generally comedic, harmless character like Ryder seriously up against Del Rio, Sheamus, Kane, Cena, Orton, Punk, etc. It's the same reason why Santino didn't progress further: people liked the guy, but they didn't like him enough to buy him as a credible threat to the top tier guys on the roster and thought the very notion of that was laughable.
Personally, if Ryder was repackaged, I think he'd have a chance. You can't deny that he's loaded with personality, he can talk on the mic, he's solid inside the ring, has a good build, is a nice looking guy, genuinely tries hard and he's still a young man at only 29 years of age. However, mid-card comedy can be entertaining, sometimes downright hilarious depending on the circumstances, but they're not serious. Truthfully, it can be painful to see comedy guys have runs with championships.