christo is a good player, and his primary talent, the reason he is an above average big 12 player is scoring. using him having a great day as evidence that spradling isn't a big 12 player is Fake Sugar Dick (WARNING, NOT THE REAL SUGAR DICK!).
according to the big 12 stats page, there are 19 players in the league that score more per game than christo. he leads the league in 3pt %.
also, anyone that thinks irving is clearly a better defender than spradling is also Fake Sugar Dick (WARNING, NOT THE REAL SUGAR DICK!). it's possible, if you added up all they each do well and do poorly that irving is a marginally better defender (it's also very possible he's not), but there's nothing clear about it.