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Charlie Savage's book "Power Wars" goes into this quite a bit.

The tl;dr is basically this: administrations before Obama definitely wanted to crack down on whistleblowers, but were limited in their ability to do so. The fact that whistleblowing related arrests/convictions have increased under Pres. Obama is largely due to the fact that we can track people and information much more thoroughly than was previously possible. In the past, you may know who had access to any one piece of information (that leaked) but you would be hard pressed to identify communication channels and specific, time-logged access, etc. Investigational tools have improved so more convictions happen.

This doesn't address the civil liberties expectations/promises of Pres. Obama, but it's one factor at play.