There’s always a risk you take when you try to build a supporting character into the lead.
As a rule, supporting characters exist to allow us to better understand the “hero” of the story. As a rule, they don’t have quite enough story of their own. As a rule, they’re not designed to carry their own shows.
But when you’re talking about Vince Gilligan, when you’re talking about Bob Odenkirk, when you’re talking about Better Call Saul, the rules don’t really apply anymore.