with all things being equal (and by things i mean "health") i think it's the extra 2-? (pick a number) MPH on the FB that a pitcher heading into his mid 30's loses that is the difference. hence my comment about the express & drugs.....
i'd rather pay $31MM for a 29 YO pitcher with 96MPH FB who may or may not blow out his arm than pay $31MM for a 34 YO pitcher with a 92MPH FB who may or may not blow out his arm.....