By FAR the biggest carrier in the Vancouver-Vegas market is actually 'none of the above', with more flights out of BLI/Bellingham, just across the border.

Not sure about other carriers, but out of Metro Vancouver area, you have
YVR AC: 1/day
YVR WS:1/day
YVR PR: 4/wk (5th freedom rights on MNL-YVR-LAS)

but you also have
BLI G4: 3/day
BLI AS: 4/wk


As for the WS numbers being higher than AC, remember that WS serve LAS from a lot of places that AC don't
AC: Calgary, Edmonton [seasonal], Montréal-Trudeau, Toronto-Pearson, Vancouver
WS: Calgary, Edmonton, Kelowna [seasonal], Montréal-Trudeau, Regina [seasonal], Saskatoon [seasonal], Toronto-Pearson, Vancouver, Victoria [seasonal], Winnipeg