There was seemingly nothing wrong with that last year, however, when the team went 10-6. The difference was that they overcame talent deficiencies with defensive takeaways and good QB play when Fitzpatrick was on the field. This year the QB play is pedestrian and the takeaway rate is vastly different. They don't have the talent to overcome that.
Last year we didn't have 2-3 OCs flipping coins to see who gets to pick the stupidest play. We also released a few of our defensive key people. And the biggest issue is the coaching staff have forgotten that there is an OL that needs attention. Not playing Gaskin, not halftime making adjustments, not continuing to do the things that work
At this point, I don't think Tua is a main area of concern. Too many other things that need fixing that could have changed the outcome of half our games. OL play, stupid penalties, confusion coming out of the huddle multiple times. Regardless of what the issues are, at this point everything falls on Grier and Flores.