The data was based on the the driver having an input of around 15 percent wasn't it? Therefore a car which was seriously lacking yet was still managed to a position higher than it should have been is what the mathematical model was based around...
This is what they said anyway:
"The highest is 11th-placed Brazilian Christian Fittipaldi (top left in above image). The Brazilian drove in 40 races over three years (the 1992, 1993 and 1994 seasons), and never once stood on the podium, yet when you look at the cars he drove, his three fourth places, a fifth and a sixth take on much greater significance. He is the son of former Grand Prix driver and team owner Wilson Fittipaldi, and the nephew of two-time Formula One Champion and Indianapolis 500 winner Emerson Fittipaldi, who placed ninth on this list."