One of Donegal's star players during the 2011 Ulster championship winning season did not accompany them on their All-Ireland journey the following summer.
After being talked out of retirement by McGuinness at the start of the 2011 season, Kevin Cassidy won an All-Star and his first Ulster championship medal, Donegal's first in nineteen years.
His contribution to Declan Bogue's book 'This is our Year' saw him blacklisted by the Donegal management. Cassidy disclosed information about the extreme nature of Donegal's training sessions, after which players were physically sick. This much we know.
In his autobiography, 'Until Victory Always', Jim McGuinness, painted as a cold, ruthless character off the back of this episode, gave his side of events.
Four years later, he is adamant he was left with no choice.
Accounts of our training. Of what we said in private about our managers. Of our team meetings. Tactics. Game plans. Performance goals. All those laid out in newsprints, and more of it in a book, and you are speechless.
McGuinness said he talked with Cassidy about the book for over an hour. In his autobiography, McGuinness indicates that there may have been a way back for Cassidy had he shown any remorse.
Before the meeting, he had speculated that Cassidy perhaps thought that 2011 would be his last hurrah and thus the optimal time for a tell all book. And that it was only when he realised Donegal had a realistic shot at an All-Ireland that he decided to stay on.
But Cassidy offered no such explanation. McGuinness said he was left with no choice.
Why expose everything we have worked to create? Kevin acknowledging that he was over the line. But still no remorse. Feeling there is nothing to work with as each minute passes. Saying again and again that this compromises everything we had been about all year. This broke the trust within the group. There is no acknowledgement from Kevin...
There is a line between keeping your best players and holding on to your best players. No other way to go.
- You're leaving me with no choice, Kevin.
Later in the book, McGuinness reveals his anger after he conducted a pre-match interview at a League match in O'Donnell Park, while Cassidy was standing beside him in his new function as an analyst.
McGuinness labelled the whole thing as a 'set-up', describing it as 'unforgivable'. The aerial shot (see below) was an additional bugbear.
Read more: Davy Fitz And Donal Og: Desperation Or Inspiration?
