Is it at all possible that before Will Bailey led the Democratic campaign in the Californian 47th Congressional District that he worked on a sports show? His wealth of political knowledge in The West Wing is the only thing that different between Jeremy and Will, yet it works.
People didn't find Jeremy particularly funny in Sports Night yet he brings comedy to the West Wing that Rob Lowe departure removed. Was this because the viewers of Sports Night wanted the ordinary, slap in the face comedy expected from the American sitcom, or was the style of comedy writing used for his character to intellectual for the show. Either way Jeremy didn't work, but Will does.
The West Wing provides comedy for the intellectual and Joshua is an intellectual comedian. The match is perfect.
I am concerned that this means that Joshua is a one character actor leaving him out of work after The West Wing ends. Those who enjoy his quick witted humour may no longer be able to, unless another writer comes up with an equally high brow political comedy/drama for which he would be perfect.