Yes, it seems we missed the opportunity once again to stop this radical terrorist due to the FBI not having enough manpower/ funds or additional surveillance tools needed. Even FBI Director Comey believes this radical terrorist could have been stopped before he cut down over a hundred innocent people. Imo, he is admitting their investigations both times of Mateen weren't thorough enough allowing him to slip through the cracks.
It may have even helped to stop the two radical Islamic terrorists in CA too if they had been able to do a much more in depth investigation. The female terrorist in that case gave a phony address that didn't even exist to those vetting her to allow her to enter the states but they never even verified it. All they had to do was Google it and see it was an empty lot. There is a lot we must do differently.
So there are a lot of things that can and must be done differently. 1) truly vetting everyone thoroughly who is wanting to enter our country. 2) our government must keep track of all of these refugees instead of telling congress they have no clue where thousands of them are.

3) more funds, agents and tools must be given to all investigating agencies in order to find those with Islamic radical extremist views. 4) Stop pretending that all Muslims in our country are peaceful and perfect people 4) Send in undercover cops to infiltrate certain Mosques if they are picking up evidence that the Imams of those particular Mosques may be teaching radical Islamic beliefs to their members. 5) Loretta Lynch needs to come forth and assure the American people they will be fully protected if and when they report to the police if they know of any Muslim/s who are advocating violence and hatred against any of us or a certain chosen group. 6) hire more internet savvy investigators to monitor the internet for hate speeches/death threats against Americans and those in the free world.
Two Islamic terrorists came from the same Mosque, one a suicide bomber and the mass shooter, Mateen. That is no coincidence.
"This was the No. 1 legislative priority of the FBI according to James Comey, and those sort of additional surveillance tools could have provided the FBI more information, which would have allowed them to identify this guy as the threat that he obviously was," Comey said.