Multiple ESPN staffers tell TMZ Sports they're in complete shock over John Skipper's sudden resignation and admission of substance addiction ... with everyone we spoke with telling us he was extremely well-liked.
We spoke with people from all facets of ESPN -- current talent, producers and past employees -- and the sense we get is that no one saw this coming.
As one current ESPNer tells us, "People are just stunned ... a lot of us truly respected him."
"You will be hard pressed to find anyone with a negative word about him.