It was super-obvious last year that his decline was already well underway. I don't know how much of his poor performance thus far has been after-effects of the spleen injury and inability to run hard for awhile. If he's not back next week we can probably just say age has caught up to him and he has fallen off of a cliff.
I had always hoped he would have a more gradual decline than what we've witnessed so far so hopefully his play picks up some soon.
I do hope we get to see Hanna more on the field because of his speed to threaten defenses down the seam.
I don't know if this offense is better without Witten due to Romo getting tunnel vision. This may be the case and he may be clogging up the middle and preventing our WRs from going after this space.
IMO, we need to get Witten running some deeper routes and starting running WRs on some more shallow crossing patterns to try and pick up some first downs as that route is hard to defend. Any one of our WRs would be a threat on this route with their RAC skills. However, I'd prefer Miles here due to his explosive RAC.