This is the annoying thing - Josh seemed to have sorted this out. From the Patriots in the wildcard game through to the Chiefs in week five we looked smooth and settled. Then the second half against the Steelers, in hindsight, should have perhaps rung alarm bells and then the regression has set in. Why?
On the flip side... take a look at Mahomes' performances between week five and week thirteen last year. Outside of thrashing the Raiders his QBR didn't go above 57.4 (and only above 50.0 twice). He was sacked 16 times and threw eight interceptions. He recovered until the meltdown in the second half against the Bengals. So there's every reason showing Josh can recover.
As I said, the saddest thing is it looked like Josh had sorted this issue out.