Actually the jury is still out on this one. Amy is qualified to comment on this, but I'm surprised at her superficial assessment on the topic.

so bad in fact, that two former defense secretaries had recommended transferring recruitment and management of DOD's spooks to the CIA. Stay tuned. The Pentagon is designed to take and deny territory.
The CIA has a long track record of clownish operations and incompetence interspersed with moments of super natural performance (the exception, not the rule). To state that DOD is more incompetent, if true, implies DOD intelligence is in deep trouble. However, the part of the sentence I bolded is where I take issue. DOD's role is broader than taking and denying territory, but even for that limited role DOD is responsible for collecting its own tactical and operational level intelligence to support that mission. That isn't the CIA's focus.

If the history books are accurate the KGB ran circles around the CIA, yet we still won the Cold War indicating that intelligence operations were not decisive. Not down playing the critical role intelligence "should" play, like preventing the attack that happened on 9/11, simply pointing out that we prevailed despite multiple intelligence failures over the years. Doesn't mean that will always be the case, especially if a terrorist manages to acquire a WMD. We need to get the problems fixed, but that doesn't mean fighting turf wars.

https://www.fas.org/irp/congress/2012_cr/sasc-dcs.html

The committee notes that President Bush authorized 50
percent growth in the CIA's case officer workforce, which
followed significant growth under President Clinton. Since 9/
11, DOD's case officer ranks have grown substantially as well.
The committee is concerned that, despite this expansion and the
winding down of two overseas conflicts that required large
HUMINT resources, DOD believes that its needs are not being
met.
The committee concludes that DOD needs to demonstrate that
it can improve the management of clandestine HUMINT before
undertaking any further expansion. Furthermore, if DOD is able
to utilize existing resources much more effectively, the case
could be made that investment in this area could decline,
rather than remain steady or grow, to assist the Department in
managing its fiscal and personnel challenges.
Bad management must be addressed, but my concern with this bean counter logic is they're missing the lesson learned over the years is always paid a serious price when we underresourced our intelligence capacity over the years, then react by surging money into it to fix it. When you rapidly expand you are obviously going to lose a degree of professionalism. Also while we may have needed to expand to our capacity to support the war efforts, in a more perfect world having adequate intelligence capability would better enable us to prevent future wars.

Amy wrote: Eyes on Spies: Congress and the United States Intelligence Community

http://www.amazon.com/Eyes-Spies-Int.../dp/0817912843

In Eyes on Spies, Amy Zegart argues that many of Congress's biggest oversight problems lie with Congress itself. Although acknowledging that intelligence policy making has undoubtedly become more partisan and rancorous in recent years, and that individual personalities matter, she shows that the root causes of dysfunctional intelligence oversight cross party lines, presidential administrations, individual congressional leaders, and eras. The author first attempts to define what good oversight looks like—and concludes that, however one defines good oversight, Congress has not been doing it in intelligence for a very long time.
This could explain the comments in the link I provided above. I suspect her book is interesting (anyone read it yet?), but also depressing for those of us who have to live in this world of dysfunction.