Bozzy wrote:

I could be wrong, but it could be the fact the runners reaching in the first place were on Cobb (i.e. walk or hit, no error committed). All future runners to go aboard via that error will all be unearned runs (and not just from that initial error, but even legit hits/walks as "he could have been out of the inning"), but I think the initial two runners count towards Cobb because "he" put them on.

Ah, ok, that makes sense.