The Irish type III is an older group, correct? If so, this could produce a larger group of down stream positives.
I think it is, but I'm not really sure. The Irish TIII site has this info on the WTY participant - Ysearch -
1. Matched the Irish Type III modal at 25 markers.
2. Was an O'Brien, the principal family of the Dalcassians.
3. Could demonstrate his pedigree originated in Co. Clare, Ireland.
4. Had tested 76 markers
They think the whole cluster is related to the Dalcassians. Here is some info on that:
The Dál gCais (also Dal Cais or the Dalcassians) were a dynastic group of related septs located in north Munster who rose to political prominence in the early medieval era in Ireland. They are desceded from Cormac Cas, or Cas mac Conall Echlúath, hence the term "Dál", meaning "portion" or "share" of Cas. In later times, for reasons of political expediency, they claimed descent from the ancestor of the Eóganachta Kings of Munster, Oilliol Olum (also known as Ailill Aulom).
Here is a paper on Irish TIIIhttp://www.jogg.info/51/files/Wright.htm