Danny Kelly from The Ringer wrote an excellent article diving in to possible fixes for the Titans offense and Marcus Mariota specifically. I’d highly suggest you check it out here. While it is written with a fantasy football audience in mind, the suggestions and takeaways he gives are more geared towards fixing the Titans offense as a whole.
I think he’s spot on with a lot of his ideas. He advocates for more play action passing from under center which is something that Mariota is excelling at this year. I completely agree here.