Can just Swiftcast Blizz2 on SMN and SCH when you're getting Disease DR anyway. With the cooldown, you're only getting one Purify per fight, and the SCH/SMN duo alone has an entire arsenal of debilitation's. BLM gets Lethargy and Blizzard II, so it truly is the god comp.

Not to say it can't be beaten, people could beat Sagat in vanilla Street Fighter 4, but it didn't change the fact that he was broken. To players of comparable skill level, the end result was apparent before the match even began. Tank/SCH/BLM/SMN is vanilla SF4 Sagat.