I think it probably is just the way he's playing him. If they just got a very good actor playing a character who's very nice but perhaps not that bright, it could possibly work a lot better. The way Ricky's playing him seems just too cartoonish, if you know what I mean. Which might work if the other characters were cartoonish as well, but they're not.
It's like everything else is quite dry and dark, and then he's just trying to be slapstick and it just doesn't fit with the rest of the show.