Quite simply, he's not the norm. Most statistical analysis, including PECOTA, uses a system of comparables. In the case of certain players... Roger Clemens, Barry Bonds, even Julio Franco... there just haven't been enough players in the major leagues like them to get an accurate idea of how their career path is going to progress... especially once a player gets to an advanced age. Putting numbers on it :"PECOTA's similarity index is a gauge of the player's historical uniqueness; a player with a score of 50 or higher has a very common typology, while a player with a score of 20 or lower is historically unusual." For the immortals: Clemens '05 similarity index: 6 ('06 top comparables of Nolan Ryan, Phil Niekro, Gaylord Perry) Bonds '05 similarity index: 0 ('06 top comparables of Ted Williams, Edgar Martinez, Carlton Fisk) Maddux '05 similarity index: 17 ('06 top comparables of Dennis Martinez, Warren Spahn, Tom Seaver) For the mortals: Prior similarity index: 22 (Don Wilson, Erik Hanson, Fergie Jenkins) Wood similarity index: 30 (Rick Sutcliffe, Jose Deleon, Len Barker) Derrek Lee similarity index: 59 (Dave Winfield, Cliff Floyd, Eric Karros)