Dye would have been playing a lot more often than the average bench player. Ortiz is really scuffling in August, getting him some time off would have been very valuable for the team in October.
Besides, how badly do we need Masterson? I know there's no such thing as too much pitching, but Buchholz, Lester, Papelbon, Matsuzaka, Beckett, and Bowden are all under 27 years old.
This team is probably one or two in terms of the best team of baseball. Having Dye's bat in the lineup would have made them the unquestioned favorite for the World Series. I'd take that in exchange for our future 7th inning relief pitcher.