Oh my goodness! Absolutely NOT! You may not cook frozen foods in a
crock pot. The temperature danger zone for bacteria is above 40-degrees
(F) and below 140-degrees. When protein-rich foods are in this zone,
bacterial growth within those foods is exponential. It is imperative
that foods move through this zone (when heating or cooling) as quickly
as possible.

You will be adding anywhere from 4 to 6 additional hours to the roast's
cooking time, with most of those minutes being well within the danger
zone. You will be hosting a bacterial feeding frenzy.

-Ron