In my view, the important part of a CSA is that the community of consumers buys the produce beforehand, for some length of time. I think the best, most sustainable model is when roasters do the same, committing to the produce of a farm for future crops. My company has many contracts that extend for years into the future, providing stability to the farmers, and ensuring supply of coffee to us.
A certain base level of quality is important, however. Even in a CSA, you have a pretty good idea of the kinds of vegetables you will get and are guaranteed a certain basic quality. You would never accept unripe or spoiled produce from a CSA. That said, some weeks the tomatoes may be better than others, or you might get nothing but zucchini. That's similar to the way these long term contracts work: a buyer and farmer can agree on a certain base level of quality, along with a certain base price, and take it from there. 80 points on the SCAA cupping form translates into coffee that was picked ripe and processed clean, so that provides the base level for most specialty coffee contracts, long or short term. Each roaster may have their own quality demands, and express them differently, and directly to the farmers. For our Direct Trade contracts, for example, the base quality is 85.
In my view, a good buyer takes into consideration the need for stability the farmer has, and makes plans for the coffee. Remember this: that by picking ripe and processing clean, using reasonable varieties on a farm of reasonable altitude, any farmer should be able to achieve an 80 point coffee. In my view, really, they can usually achieve an 85. So, if a good buyer commits to buying the coffee for years in advance, that produces the most possible stability for the producer, and allows them to experiment and invest in quality improvements. If a buyer/roaster can get his community to support that sort of work (CSA stands for "Community Supported Agriculture", remember), then you have the perfect CSA for coffee.
Specialty Coffee Association of America