You're right, she's either in it up to her neck or a complete waste of space as a manager .Or maybe both ?
Well, yes: the "all of the above" option is a definite possibility!
There is something-else worth remembering about Brooks, though: one of the things she's best known for (especially during her time with the NOTW) is a strong interest - some might say "unhealthy obssession" - with paedophiles and child killers. She was instrumental in promoting the campaign for "Sarah's Law", for example. (And interestingly, Sarah's mother is now thought to have been a hacking target...)
Now: is it really credible the that Brooks was completely uninvolved in the investigations into both the Dowler and Soham cases?