I wold put this another way. I say she’s still a good manager, because not only does she manage her staff well, she insists that they follow procedures and the law, so the cases will be legally airtight.
She sucks at being a politician. She sucks at things good managers really should kinda suck at, like tolerating incompetence from others (usually cops from other divisions or prosecutors), or turning a blind eye toward police misbehavior (well, except for her own, of course, and AFAIK her misbehaviors are not criminal) like beating prisoners .
Ignoring the implicit criticisms of politicians and the slander that good managers should tolerate incompetence, I still say that Brenda was overall a bad manager. Yes, she could close cases; yes, she could inspire loyalty and accomplishment from her subordinates. But overall she acted in ways that were bad for the organization. The case with the gang member whose murder she all but solicited is characteristic. She caused tons of problems for the LAPD in that case, and Captain Rayder’s criticisms of her actions there were right on the money.
I would argue that her management skills weren’t involved with that action at all. She could have done essentially the same thing as a street cop – allow one guy to make some extra phone calls from jail, that is the one guy who she knew would call his buddies to kill the other guy she wanted dead.
And no, I didn’t say that good managers tolerate incompetence, I said good managers would be bad at tolerating incompetence.