In “Better Call Saul,” fans catch more of Jimmy McGill’s backstory as a young man in Cicero, Illinois via flashback scenes that explain how he wound up in Albuquerque in the first place. In Illinois, Jimmy runs scams to make quick cash and earns the nickname “Slippin’ Jimmy” for his efforts in the art of falling accidentally-on-purpose (via the Breaking Bad Wiki).
“We thought he must have taken a lot of bad hits on the ice of Chicago and he probably messed up his knees falling down all the time,” writer Thomas Schnauz told The Hollywood Reporter. “When we did it in Breaking Bad we didn’t have a reason that he had bad knees, but it’s nice when we can tie those threads together.”
The character’s background as “Slippin’ Jimmy” proves to be an early iteration of the Saul Goodman moniker — the persona Jimmy McGill adopts when he’s involved in criminal activity. Throughout the series, Jimmy’s desire to shine as a legitimate, above-the-board lawyer is thwarted by characters like his brother Chuck, who never believes Jimmy has fully grown beyond his scamming days. Jimmy’s — and Saul’s — bad knees being a result of one too many scams pulled may serve as small but clear evidence of that dilemma.