The change in the relationship between Marrone and Coughlin is totally believable to me.

Marrone was raving about Coughlin every other press conference. That was until mid-season last year, towards the Carlos Hyde trade time.
This year Marrone mentioned Coughlin (Coach like he loved calling him) much much less. Apparently the disconnect was already there in the summer when Marrone softened his training camp approach to try and prevent the injury bug after last season and Coughlin was against that.
The biggest sign of frustration was when the Ramsey trade happened and Marrone was left alone the entire time having to answer questions about that and he openly said "I wish someone who's in charge would be here to talk with you guys...I can't give you those answers".
He was clearly frustrated (as he should) that once again the FO put him out there to explain things that are not under his control.
To my memory he never praised or spoke about "Coach" again since the start of the season.

Dilla has been right more often then not lately and the story about the Foles benching sounds believable to me. Players probably felt those things as well as it was often reported that many of them don't like having Coughlin around (there was an interesting interview with Bouye or Campbell at the end of last year where they basically admitted that the way Coughilin dealt and put pressure on players wasn't appreciated and players weren't all reacting well on the field because of that. Coughlin said he would be "living in their shoes" talking about the players and the staff when he was hired...that possibly backfired).

---