We can take it as given that potential bad guys have been stopped by the combined efforts of the TSA and other agencies. The questions is whether it's been the barbaric security theatre by a cast of hundreds of thousands or hard work by a few people based on human intelligence.
TSA does not have a track record of stopping a single bad guy. It was meant to do that but it hasn't, in all the years of its existence.
It wasn't designed to conduct surveillance, gather intelligence, produce scary propaganda, it was designed to catch the guy with the bomb red-handed, as in "Oh look, there is a bomb in an x-ray machine!" kind of situation. That that has never happened. So what do they do? As a proper and decent US govt. agency that they are -- they increase the number of rules and ask for more funds...
But no politician will ever dare dismantle it. Nobody wants to be "soft on terrorism". In case of an attack they need the TSA as a scapegoat so they can point to it and say "look, we are spending all these money, we have all the people groped and x-rayed, there is nothing more we could have done, it is _not_ our fault"
So I'll agree that FBI, CIA, NSA, air marshals, the flight crew, and just regular citizens have stopped bad guys. But not the TSA.
