Thanks for the link Maud, an interesting article.
The writer however makes rather a large generalisation by saying this seasons harvest will be lower quality as many factors impact on quality - timing of the harvest, time between collection and extraction and the extraction method to name just three. And of course quality is a subjective term, recent research suggests that the oil from early-harvested green olives is healthier to consume because it contains higher levels of Polyphenol -which is now reckoned by some authorities to be one of olive oils most beneficial ingredients. Most tasters however would describe the oil from early harvested olives as having a bitter taste, preferring the fruitier taste of oil from olives picked later.
For most commercial growers in Greece it's a balancing act between quantity and 'quality', up to 80% of the olive oil production from Greece is Extra Virgin Olive Oil (EVOO) so growers here will be aiming to produce oil which, among other things, contains no more than 0.8% free acidity, (or 8 lines as they say in the local olive press) generally speaking the earlier the harvest the lower the free acidity percentage, the later the harvest the higher the oil yield - so its something of a trade off between 'quality' and quantity, particularly in years like this when a combination of hot summer and very little rainfall has reduced the potential harvest.
On the subject of olive oil quality I was told yesterday by an ageing Crete cook that she regretted it was no longer possible to find the oil she had used in the 'old days', oil produced from olives which fell naturally from the trees and probably sat rotting in the nets for weeks before being collected and pressed - this oil she said, was far superior for cooking than today's EVOO's
For anyone seeking more information about olive growing and olive oil this site is a good first stop:- http://www.oliveoilsource.com/