I was not aware the ISI gives statements, are you sure we are talking about the right organization here?
Terrorists were staying in the US for years, they learnt to fly there and then hijacked commercial air craft, crashing them into the WTC and the Pentagon. Changes in the CIA? Nil. That's just one case, the US doesn't have a 2250km long highly porous border with the badlands of Afghanistan. For every attack that succeeds, about 10 are thwarted, it's an acceptable failure rate in my opinion. Especially when considering that domestic security was never meant to be the objective of this organization, it has had to adapt with the changes and did so well enough.....