A huge problem in DC is that the overwhelming majority of the staff's are Dems, as I found out when I attended the inauguration in January. I learned that Murkowski's office is almost all Dem and voted FOR Hillary, while a US Army captain in the Army Corps of Engineers told me he wouldn't dare speak well of Trump, as that office was totally for Hillary. 
So I can easily believe the WH has staff of the same ilk and the sooner Kelly can rid the WH of Hillary supporters the better. 
I suspect Preibus did a very poor job of vetting, and if Kelly cleans the place up, then all the more proof Preibus was the wrong guy.