I'm guessing that Holland did not show them much or he would have been called up.
Holland had an ERA under 1 in AA, so it's hard to see them not giving him some sort of a chance. The problem here is that Holland wasn't on the 40-man prior to September 1, so the only way he can become playoff-eligible is if a playoff-eligible pitcher gets hurt. They'd also need a space on the 40-man, so someone would need to be DFAed or moved to the 60-day. So unless someone legit gets hurt badly enough for that or they can fake an injury that would work, it's tough.
I do wonder if Ross being scratched over the weekend was Step 1 of this plan - he's playoff eligible, a pitcher, and not good enough to merit a spot on the playoff roster. Guerra might be another candidate for the same treatment.