Two points here.
[1] FBI's problem in the Clinton years was spelled F-R-E-E-H. He was weak and dependent on Clinton (Gee, why was he selected?), so he allowed Clinton to politicize the FBI in ways that had to have JEH spinning in his grave.
[2] The FBI is drastically overcommitted right now. When Mueller tried to get them out doing bank robberies, the locals objected, because that would have increased their workload by default and given them more budgetary/staffing problems. So, end result, Mueller backs off the idea.
Right at the front end of this spree, every agent in sight of DC is called out on weekend duty for the stupid ararchist 'protest' at the IMF. Thus, when the shooting spree hits, the offices are decimated with agents taking CTO off (since they aren't paid for OT).
On top of that they have a ton of counter-terrorist stuff to get on top of and then add these two Mohammedan morons and the affirmative action 'keystone kops' routine to the mix. [And remember some percentge of the FBI's own staff is set aside for AA -- lots of little incompetent females running around saying "I are an FBI agent."] So, with all those handicaps, it is not surprising that the ol' horse doesn't run as fast or as well as it did in Hoover's day.