I'm not sure I can agree with the 80-90% viability after 4 months since they leave the plant at 95%, even though Wyeast guarantees it for 6 months. And not knowing how it was handled getting to the store and into their fridge, as well as the package not swelling too much. I think Mr. Malty putting it at 10% is a little extreme however.Only problem is that it is going to be severely underpitched.
I don't see how. At four months old, the smack packs were probably 80-90% viable. 3 * 80 billion / (19 L * 10°P) = 1.3 million/mL-°P.