Whittling down who I think it isn't:
Wood is the least person I'd expect to have said those things. Wood has been the player most vocal of supporting Lancaster since the end of the WC, I doubt he's trying to secretly undermine Lancaster, saying that players don't respect him.
I don't think any of Robshaw's club mates would say those things about him. So I don't think it is Care, Easter, Marler or Brown.
Tom Youngs owes a significant amount of his success to Lancaster, so I doubt him.
Don't see Ben Youngs or Joe Launchbury as being political/tribal enough to have said those things.
Farrell is a Lancaster favourite, so I doubt him. Lancaster has also stuck by May through some poor performances, so I doubt him too.
Now players I think it could be:
Wilson: Aggrieved about totally being left out when it came down to the World Cup?
Morgan: Perhaps annoyed at being dropped when he was in poor form for Gloucester but good form for England and I can see him having a fairly strong opinion that Kvesic should be ahead of Robshaw. But on the other hand, Lancaster did trust Morgan to come back well from injury and picked Morgan at the World Cup. So I'm torn on him.
Lawes: A lot of reported squad discontent about Burrell being left out, I can see Lawes being particularly upset about his club mate not being picked.
Billy Vunipola: Already said some pretty damning things about the England management.
Haskell: Very experienced, fairly vocal, probably felt he was underused by Lancaster. I think he's more tactful than this though...