The Other character assassinations
The most obvious and talked about character assassination in the series is Toby. And while I don't think it's as bad as people say, it's hard not to agree that he was absolutely changed for the worse. However, I wanted to talk about the other, lesser character assassinations of the post Sorkin era. I have a few examples:
Jed Bartlett - We see the president go from a strong serious man with a folksy dad-like side, to a bitter and depressed shadow of his former self.This is an understandable direction to take a character, and I really appreciate the disability representation we get from the progression of his MS (side note: disability rep is something the show does very well, consistently. usually better than anything you'd see today honestly). I find in seasons 6 and 7 any time we cut back to the West Wing it's just a complete drag, constantly wandering around aimlessly. That may be the point, and if so it's artistically interesting I suppose. But it's not what I'm here for, and it's not who the character was.
Leo - I always think of post Sorkin Leo and post book Tyrion Lannister to be similar cases. A brilliant political mind that, after new writers are brought in, makes a series of out of character mistakes and overall loses their edge. Leo goes from a close friend passionately and calmly arguing against an incursion with no exit strategy, to a crazed jingoistic suit yelling at the president that he has to go into a war blind because "we don't always know how it ends." Not to mention going from a paternal figure in Josh's life, accepting him for his PTSD because Josh accepted him for his addiction, a figure who would always have his back... to nearly firing Josh over what is frankly a minor political mistake in the series.
Will - This one may be a little controversial, because I know not everyone is a fan of this character. Frankly, it feels like they never stuck to an idea with this guy. He becomes the dork of the group and sister gets added in but it never really lands so she completely vanishes a la Mandy, he gets put in charge of a bunch of pretty interns in a strange gimmick, then he's randomly ripped (??) and part of the military which only comes up like twice, then he leaves shockingly fast to become captain of the wiener squad with Bingo Bob, then there's some weird dynamics with him Josh and Donna, then... press secretary. Sure. When he was introduced he was this savvy and extremely dedicated political mind who wasn't afraid to get in Toby's face, or the president's for that matter as an intern. For 2 episodes, Will was a very exciting and fiery addition to the main cast, then he's very unfun.