Schrader and Harlin did not fail on either account for direction. They are both good directors (however, certainly they are not in the Friedkin arena, IMHO). The problems, again IMHO, for both productions was the out-of-sync, chain-breaking “unseen good versus evil” premises that swayed too far from that of the The Exorcist’s basic concept. The true horror was the writing in both scripts, editing, and overworking of CGI effects that were both implausible and laughable.
No one could save either version no matter how much money Morgan Creek poured into them. Ultimately, the prizing-winning cash cow needs to be led to pasture to bask in the glory of their achievements. More here.