Gene Roddenberry had some good science fiction authors contributing scripts in the beginning. Gene also had the wisdom to rewrite the scripts so that they all had consistency and conformed to his idea of story and characterization. Fortunately, this was still before his later idea of idealized humans getting along to the point of no conflict in TNG. Unfortunately, all of his rewriting started to alienate good writers who didn't want to come back to write more scripts as the series continued on. By the third season, Coon, Fontana, and Roddenberry had all stepped away from the day-to-day hands-on jobs they previously did and just contributed the occasional script. The overall quality of the scripts suffered from lack of attention and continuity with the earlier seasons' scripts. It was said that the new story editor asked someone on the set one time "Remind me again what this transporter thing does again?" If it weren't for Shatner and Nimoy stepping up to protect their characters (and helping the show by doing so), it would have probably been worse than it was. Freiberger said once that he honored most of the writing assignments that Roddenberry had assigned for the third season before he came aboard, but they still lacked the polishing the scripts needed before they were filmed. Personally, I don't believe that all the blame can be laid at Frieberger's feet. It was a gradual decline that started since the first season as key people (sf authors, Coon, Fontana, Roddenberry, Justman, etc.) started checking out.