what else, unless you look to price strikes and tenors which are illiquid. Your own model should be derived from metrics other than traded prices else you end up predicting the same that you used to derive your model.
Gentlemen, thanks a lot for your contribution. Now I can finally pull the plug on this chapter and move on.
It's incredibly arrogant (and very human at the same time) to assume you start in a domain suffocated by competition like perhaps noone else and the first idea you get as a clueless newbie is going to be the jackpot. It's arrogant and stupid because it never works. It's human because can't be otherwise, if you wouldn't foolishly believe in your inexistent prowess you wouldn't even embark on the perilous 10,000 miles journey to find the holy grail of trading. After 20 years of experience in the domain I can tell you that even after you get to EXPECT the unexpected, what you eventually find that actually works still surprises you. And no, it's not the original idea you start with, far from it.