He hasn't allowed any of this to happen. It was a problem before he got there, and these agencies are doing a fine job of destroying their own credibility without any help from him.
You can't fix all this sh!t in 15 months. The FBI will very likely have to be dismantled entirely. That will be such a political hot potato that it probably shouldn't even be considered until after 2020.
May I remind you that congress has had to threaten Sessions with contempt of congress in order to get him to respond to their LAWFUL requests for information in connection with their oversight duties. He was obstructing congress and thwarting a legitimate inquiry. That’s VERY serious stuff my fried.
Sessions is protecting someone and hiding something big.