Howell is definitely a wait and see, but he has these factors going for him.
- New O Coordinator and system
- awesome receivers and Antonio Gibson
- good offensive line
- Washington coaches obviously believe in him
There is enough here to justify being bullish on Howell IMHO.
I agree there are some positives. This post made me curious, so I looked at the PFF team grades (regular and postseason) last season. Here is where Washington finished:
- Overall - 77.2, #23
- Offense - 67.6, #27
- Passing - 53.4, #30
- Receiving - 75.1, #15
- Pass Blocking - 61.7, tied for #26
- Run Blocking - 55.6, #24
- Running - 77.2, tied for #24
- Defense - 74.2, #13
- Run Defense - 61.1, #20
- Tackling - 68.0, #10
- Pass Rush - 71.9, #13
- Coverage - 83.1, #8
- Special Teams - 90.4, #2
The passing performance was terrible, so the bar is low for Howell to be an improvement, especially since this reinforces the targets are good.
The pass blocking and run blocking were bad, which didn't help their QBs and RBs last season. However, they upgraded their OL in free agency and the draft.
No one should be surprised that a Ron Rivera team would have its strengths in defense and special teams, not offense. Looking at their offseason moves, the defense should be very good again. As you point out, new OC Bienemy could help the offense.
Signing Brissett was better for Howell than many other alternatives, but he is a capable backup. Rivera could be on the hot seat and thus could feel pressure to move the Brissett if Howell falters. That is really the only negative I see at this point.