I really don't know where you are getting your stats from but I'd go and check again before claiming Bolden has zero incompletions because that is not the case. Similarly, I have no idea where you have the 6.9 and 3.9 numbers from because they make no sense whatsoever based on PFR data.
What it boils down to is Michel is a superior talent when it comes to the bread and butter which is power run. Also since they have made it a point to throw 2-3 targets to him which is for the last two games he has outgained Bolden easily there as well.
So if you think we can just stay with shotgun runs, throw out the portion of the playbooks with power running because it has looked not particularly efficient so far and keep finding ways to scheme Bolden free to make him effective then I don't know what to tell you.