If this year's performance is based on 1999 stats, and statistically speaking, you can expect performance at or near 1999 stats, then the difference between what a player is doing so far this year, and what he did last year has some guidance as to what to expect in upcoming games. This is strict logic, not including sickness, divorce, age, attitude, etc. If a particular player is not hitting up to his 1999 stats, it would follow that he may improve, and the inverse is expected if he is playing "too well". This IS SUBSTANTIAL and can be used in a statistics-based situation.