Dreams and Nightmares: Jeff Mathis
For the second string catcher, Jeff Mathis a nightmare season would include a sub .200 batting average, much like Napoli's nightmare. The difference is Mike has enough power and walks to have some value even at that level. Mathis does not. It is highly unlikely that Mathis will get the playing time that any of his CHONE percentiles list him at.
For playing time, the question the system is trying to answer is "how much playing time has this guy demonstrated he could handle". This is an easy question to handle through a program. Another question would be "how much major league playing time will player X get". This cannot be answered as easily, as it not only requires knowledge about the player, but knowledge of how 30 team management structures will make their decisions.
As for the Mathis dream - In his 90th percentile, Mathis would essentially be a league average hitter, excellent for a catcher. A .257 average, 17 homers if regular playing time, and a .334 OBP/.441 SLG. It would be a nightmare for Angel fans if Mathis got that much time, as it would mean Napoli must have suffered a serious injury.