I had the chance to visit with John in 2012 and confirm what Bill says. The yields are abysmal. The set on the Grenache alone had to be well shy of 2 tons per acre. Cool climate with proximity to the ocean, wind-swept hillsides, poor soils, and low-yielding selections all play into this.
To expand on Larry’s point, there is both a ceiling and floor for yields as quality is concerned. At Alban, it seems the floor is low. I’ve never experienced a phenolically underripe Alban wine. The vines are in balance at low yields.
As for the Oakville bench (where I’ve made wine), 2.5-4 tons is a low sweet spot in my opinion for mature vines. You would be surprised (or maybe not) at how many vineyards carry 5-6 tons per acre and make very good wines, and at how many vineyards in the flats are carrying 6-8 tons per acre.
All things not being equal, in my experience Rhône varieties do better at lower pounds per vine versus Bordeaux varieties. Depending on climate, clone, exposition, vine age, spacing, and vegetative vigor of the vine, I find that Syrah does best at 2.75-5 lbs per vine, whereas Cabernet can make great wine up to 8 lbs per vine. With all that said one cluster per shoot doesn’t necessarily make better wine. Cull crop down to 3lbs a vine in warm terroir and you may see elevate IBMP and high glu/fru. A losing combo if you ask me. You have to know your vineyard. Apples to oranges.
