As you recall, we need the standard deviation of the eval scale to be 1.5 times as big as the experience standard deviation. Every specialty is different, with different eval stats and experience stats. Watch out for callers who say their buddy's raw eval average converted to a different value that their same raw average did. They'll be in different specialties. Some callers will want to know why their '98 scores very similar to their '97 score convert to different values.
Every year is different.
That is, the MAT average eval and average experience will vary from year to year, as the candidate pool changes from year to year. Therefore, the same eval score will not convert to the same pre-board factor year to year.