The OL is actually doing a much better job than they get credit for. Tanner had some really nice pockets all game long. As has been documented, the WR group is improving as well. Many WRs are open but Tanner doesn't see those reads.
Tanner grew up in a spread/air raid system in HS and pretty much what Anae morphed him into in 2015. Basically make 1 read then scramble. He hasn't progressed well enough to make multiple reads and throw the ball away when he needs to.
Is the OL perfect, nope but much improved. Are the WRs perfect, nope but much improved. Tanner...seems to have regressed.
Now we are seeing what was rumored last year, that Tanner wasn't picking up the offense very well and thus Taysom remained the starter all season long.