I agree with almost all of that.... Except when you talk about Unga having to "compete" with other RBs... Meaning what? Share carries? Over their first two seasons, Unga had over 100 MORE carries than Jamaal has. He had two seasons with 240 or more carries and Jamaal's most is 217. You can't really use the argument that Williams was "fortunate" to be in a running offense because he got fewer carries than Unga did.
If you're talking about total yards and competing, Williams has had to "compete" with his QB who had over 250 carries. It has been lopsided in favor of Unga. He HARDLY had to "compete" with others. Nobody stole carries from him. He was the main man.