Fair question.
You already know about the awards Frost received, the accolades, and national recognition this offseason. However, it's hard to see how Frost is or could be worse that Riley and his staff. Riley never has done what Frost has done is less time. I also find it silly to think a 0-12 UCF team had "special talent". Teams with that kind of talent don't go 0-12. I'm sure there was talent, but not 13-0 talent without being coached up. Lets not forget a likely primary reason for such a great season as UCF was their QB, Milton who Frost recruited as a low 3* out of HI. Frost helped turn that kid into a Heisman finalist as a true Soph. He also brought in CB Mike Hughes in 2017 and has a offensive scheme that dominated in 2017. That is all on Frost, not the previous coaching staff at UCF. The previous coaching staff resulted in a 0-12 season and a crap culture. Frost fixed that culture in 2 seasons. He deserves a huge amount of credit for that.
Probably the most impressive thing about Frost is he QB development (most important position on the field). In 3 of the last 4 years Frost's QBs have been ranked in the top 2 of passer efficiency - Mariota (2014), Vernon Adams (2015), and Milton (2017). Now at NU he'll have Gebbia, Martinez, and McCaffrey. A nice group to move forward with.
The biggest change, and you can see the results now, is the strength training. It was crap under Riley. Frost and SC Duval demand results and are getting them. That will show up on the lines and will only get better in the coming years. I'm not saying NU will be Wisc or even Iowa on the OL, but they'll be much better soon and with that offense they run they'll put up a lot of points. The D will be aggressive and create turnovers. The D will take longer to get the right pieces in place as NU is thin at CB and edge rushers, but Frost and his staff can recruit and have shown they can develope guys to get to the QB and create turnovers. UCF was really good at that.
All of that said, no one knows, but if you look at past trends as future predictors it's hard not to get excited and see how much better Frost should be than Riley.