What happens when the NSA inserts their taps

Have a look at Level-3’s response time from the other day.  During this time, I noticed some sites were slow or non-responsive. 

Why are there no decent stories on how the NSA taps at the ISP level?  It’s not like Google is saying “come on in with your network taps, boys!”. The tapping is happening at Level-3 and other ISP’s.