Robert Parker, the American über-guru whose pronouncements on wine - particularly red Bordeaux - have made the reputations of producers and vintages since the early 1980s, has just announced his ratings of the 2009 Bordeaux harvest.

Following a series of "vintages of the century/millennium", Parker has had to proffer scores which exceed the maximum possible on his 100-point system.

Some of Parker's greats of last year (none yet properly blended, all about two years from being bottled and decades from their plateau of maturity) have been rated 100*. This is either an acknowledgment that he has been too lenient in the past, or else that 2009 has outperformed his nec plus ultras by a distance too great to be ignored.

All this would be the subject of an arcane April Fools' Day prank if it did not affect the income of Bordeaux's top 100 properties this year by somewhere between R2bn and R5bn.

Parker's influence was supposedly on the wane, with analysts pointing out that his occasional lower scores for top properties merely tarnished rather than condemned their commercial prospects. However, when there is a generally good consensus about a vintage - such as with last year - and the focus is on estates with an established track record, Parker has proved he can add white heat to the already seething levels of interest.

Part of what makes him so influential is the market he addresses. He introduced a whole new generation of American consumers to the joys of French wine, simplifying the nuances of the subject with his so-called 100-point scoring system. According to Parker and his acolytes, 94 was discernibly better than 92, a judgment he was happy to make while the wine was effectively in utero (in other words, in cask).

In the 1980s Parker's ratings gave the Americans the confidence they needed to out-purchase the Europeans (and send the prices of top Bordeaux reds from under 10 a bottle on prerelease sale to levels that this year may even reach 200 times that amount). More recently, with the Far East now Bordeaux's biggest customer for trophy wines, Parker is back with a bang. Demand from the Orient is apparently fuelling the 2009 campaign prices as a seemingly infinite resource chases a finite amount of stock.

There is no one and nothing as influential as Parker elsewhere in the world. A few high-profile critics - Jancis Robinson in the UK, for example - may offer the thinking man's version of the Great Man's ratings but their nuance and very lack of simplicity counts against them. Team efforts - whether from wine competitions or guides like Platter - don't have the force of personality to sustain them. For consumers who wish to abdicate all responsibility while making their wine purchases there isn't even a surrogate god.

The SA Wine Index (www.sawineindex.com) - recently launched as a one-stop point of reference - hopes to fill some of this void. The brainchild of Izak Smit, it evaluates certain cellars and their wines by reviewing their performance across a number of tastings. Competitions and guides provide the raw data, which the system then manipulates by applying favourable loadings to some, and diluting the influence of others.

Though formally launched, the index is still in its infancy. A number of well-known properties have yet to be reviewed - raising the question of what criteria were applied in the decision to assess Bouchard Finlayson and La Motte, but not (yet) Vergelegen and Kanonkop.

In its current form, the SA Wine Index is a shadow of its potential. Once it has been fleshed out, it could be as much a guide to site as a measure of winemaking performance.

It won't be infallible - averages of averages lack that kind of precision and the subject doesn't lend itself to that kind of treatment. It is, over and above everything else, the other extreme of the Parker model - panel, not personality, providing the impetus - and for this reason alone it should not be dismissed.

From Business Day, 12 May 2010