Based on what I have see with CA and WA blacktails I think a couple things are going on. There are mule deer around on the west slope of the Sierra, but on the coast they are certainly no closer than mulies are here.

The CA deer are, at least in my experiance, smaller bodied. But, in general, they have bigger antlers. I NEVER saw a spike in CA; first antlers were always forked-horns. I was mainly hunting along the central Sierras, including foothills. Here, I see spikes all the time. At least when i was there, the ninimum legal deer was a forkie.

I think that, in general, the minerals in the soil lead to bigger antlers down there. I don't recall seeing any as heavy as I've seen in WA, and the color of a nice set from WA is amazing.

Also, like my dad said, he cooked those antlers for weeks and they still didn't taste too good. The deer I have eaten from up here in WA sure cook up better. I think the wetter climate has a lot to do with that.