Saul Goodman's diploma in Breaking Bad is a hell of a lot different than what we saw of Jimmy McGill's diploma. Master of Arts? Yeah right, not when a law degree is J.D. Even Skyler White caught that bullshit a mile away when she was first introduced to Saul Goodman in Breaking Bad.
So the only explanation is Saul Goodman represents the access to criminal networks he has. Which means I wouldn't put it past Jimmy McGill to forge a diploma and use the Saul Goodman moniker as a way to get back into lawyering. No way in hell he's waiting another year.