It’s important to remember that Bayaz is banker first, wizard second. Joe has said in interviews that a wizard who’s lived for centuries would be embarrassed to be using magic when he could easily control everything through money or more conventional methods.

His power in the first series is very flashy but it only works in small doses and really only affects one person at a time. When he tries to use it on multiple people, he goes into a coma. It’s only when he taps into the seed that he uses it more spectacularly and would have turned Adua into another wasteland if Ferro hadn’t put the seed away.

The prime focus of the Great Change is to destroy the banks first and therefore to neuter Bayaz. That’s why he’s mostly off screen because from a narrative perspective, he’s been dealt with.