No, YA is for non-space-restricted economy awards.
If one knows (or can establish) the relationship between the the standard award business class (CS) availability and the upgrade availability, then upgrade availability can be estimated using that factor...
So far in all the searches I have tired if it is CS+ then that also means that there is a upgrade fare available from a slighly discounted fare (B class). If it is a CA+ then it seems that there is a upgradabe available from a full Y fare.
If it is CA- and CS- then you are compeltly SOL.
Do others see the same thing for upgrades...