Because few county council wards have a proper general election type competition with all the main parties contesting each seat, local elections are not a real test of what might happen in a general election to either Westminster or the Bay. The best indicator isn't the votes cast, but the numbers of candidates that a party can persuade to stand in each county.
In this respect Plaid Cymru seems to have been weekened by the coalition with Labour rather than strengthened. Apparently there will be fifty fewer Plaid candidates standing this year than there were last time the Welsh counties went to the polls.
It's not just fifty fewer candidates though. In Gwynedd, Ynys Mon, Ceredigion and Carmarthenshire (Plaid's heartlands) Plaid is boasting that it is standing more candidates than ever before. So if Plaid is 50 candidates down on 2004, overall, but is competing in more seats than ever in its heartlands, there is a strong indication that the party isn't doing too well outside the Welsh Speaking West.
If Plaid really wants to challenge Labour as an alternative "lead party" in Welsh politics, it must fly the flag throughout Wales. Shrinkage in party candidate numbers outside the western heartland doesn’t auger well! Just one candidate in the whole of Blaenau Gwent, for example, (same number as the BNP)!!!!
If Plaid wants to be serious about being considered as the "Party of Wales" and the biggest Assembly party in 2011, it should have candidates, if not in all Welsh wards, in at least a majority of wards for each council.