Well - whatever they do in that spot, if it works we love it, if it doesn't we will gut him for it. If they run a trick play, we are literally calling for Turner's head. Unless it works
I like to think that there is a group of people (yourself included) who are fairly careful not to do that though. To try to keep it even and fair.
On my part, I don't think looking at Turner's performance over years and questioning the 3-year extension is unfair. I don't see the statistical ranking or growth in coaching, or even the competitive market (there was no clamor for his services) to justify that.
As for his individual playcalls, if he breaks tendency and fails, I think the group of people who are complaining here would be fair (or be called out!). That would be ok. It is only that if a bunch of people sitting in chairs at home know what Turner is going to do, at least to a great extent (maybe not exactly who the primary look will be, but perhaps pretty likely), then DCs will know too.
You posted earlier about how Turner got stuck with Haskins. He also requested Allen because of Allen's familiarity with his playbook. It is a symbiotic relationship between playcaller/OC and QB too; observationally, Turner is not making his offense easier for a new QB to pick up. What is the result? Every time we have a young QB, they are going to look bad. Every time we have a QB who is new to the system, they look bad. Alex Smith is generally highly regarded as one of the smarter QBs you could have. He has been by far, I think, the most successful QB in Turner's system. I don't think that's coincidence.
A lot of this criticism is based on a lot of observation mixed with statistics too. I am trying to be fair to Turner, but at the end, I just see too many arrows pointing at him. I hope his move to the booth will awaken some sense but at this point I don't expect it.