Brooks is good, but he needs help. Barton is so-so. He does some good stuff, but he's guilty of not being Bobby or KJ, which makes him an easy whipping boy. Taylor has regressed. Chenna is good. Mafe will be good as he gets more reps; he shows flashes but is inconsistent.
Diggs is good. Ryan Neal is good. Bryant is improving as is Tariq. We need more consistent play from Jackson or whoever else plays that other CB spot.
The biggest issue is the D line and needing more help in the LB corps. Al Woods plays great but is getting older. Poona seems better suited to the 4-3 so far. Beyond that...meh.
Brooks has been awful this season, Barton has been even worse. They're not good or so-so this season, they've been absolute dumpster fires. Bar none this is the worse LB corp in the NFL -- let's not sugar coat things here.
It is worth mentioning that Brooks is out of position. He played ILB in college some, but it seemed he spent most of his time at OLB in a 4-3 system. He looks like he doesn't know where to lineup half of the time. Part of me wonders how much did Wagner contribute to his success last season. Wagner was extremely good at diagnosing plays and getting everyone lined up correctly.
As far as switching back to 4-3, I don't think that fixes our problems. I suspect that these issues run much deeper than just the 3-4 alignment.