Boston Legal...the various change overs I think hurt the show dynamic and allowed Kelly and his writers to focus more on Shore and Crane which isn't neccessarily a good thing since I think their relationship was handled great in the first two seasons with the large ensemble.
With a David E. Kelley series, you
have to expect a revolving door cast. It's just the way he works; he introduces new characters to see if he can get something interesting, and when he doesn't he replaces them with others.
The Practice, at least until its final season, was an anomaly on his CV; the cast stayed stable pretty much throughout its run, with the only major blip being the Ron Livingston period.
As for
Boston Legal specifically, the cast departures certainly were more pronounced than the Kelley norm; watch the first half of the first season as Kelley and Bill D'Elia are trying to figure out what works and what doesn't, and you'll see that the signature
Boston Legal-ism -- the balcony scene -- doesn't turn into the episode capper until around episode five or six. The first season was a concerted effort to figure out what the series
was; strangely, for a legal series, Kelley's plan was to
never go in the courtroom. And, of course,
Grey's Anatomy scuttled the back half of the first season, which led to episodes being reshot and restaged, or edited all to pieces, in the second as the extant footage allowed.
I'm not sure that the cast departures had a major effect, however. Yes, it's frustrating to see a character just up and vanish -- Lori and Garrett come to mind -- and departure of Rene Auberjonois at the end of the third season was unfortunate, but I didn't mind John Larroquette as his replacement in the ensemble. The misstep Kelley made, however, was in a cast
addition with Jeffrey Coho in the third season. This is no criticism of Craig Bierko or his character -- I liked Coho a lot, and was miffed when he left to go back to the New York office -- but Kelley had a new toy on the table to play with, which he did, only Coho took the oxygen away from Alan Shore and Denny Crane. Rewatch the first half of season three, and their lack is
palpable.
Yes,
Boston Legal had a large, revolving door cast. But the show had a five year run, and in the final two seasons the cast was stable, as stable as it had been the two years previous, just with a different cast. The show's treatment had more to do with ABC's antipathy toward the series than any audience erosion due to cast departures. I'm not sure that I would call any of the casting changes with
BL "catastrophic." Now, had Spader and/or Shatner left the series, there wouldn't have been any reason to watch.
