Pakistan's ambassador to the United States, Husain Haqqani, explained it this way: “If Whitey Bulger can live undetected by American police for so long, why can’t Osama Bin Laden live undetected by Pakistani authorities?”
Now it turns out that Whitey Bulger was living quietly in Santa Monica for at least fourteen years. One commentator observed that the apartment was only about three miles from the FBI's Los Angeles office.
It's probably just coincidence. I can't imagine the FBI were any more embarassed at the Pakistani ambassador's words than they already were about not finding Bulger for sixteen years.