Puyol gave a interesting interview to la vanguardia:
http://www.lavanguardia.com/deportes/futbol/20150627/54432559147/carles-puyol-seguir-sin-cobrar.html
Some parts translated by
https://twitter.com/AddictedToBarca
Q: "What day did you decide to leave it all?"
Puyol: "It wasn’t a day, I am not one to throw in the towel quickly. But after the last surgery, when the knee started to secrete liquid, I saw that I couldn’t compete nor train. Tata Martino wanted me to play, but I would tell him: 'Put in others, they are better.'
Q: "Sporting director, coach, agent?"
Puyol: "They’re all attractive, but now it is time for my formation. I did the course of Sporting Director and now I’m going to take the coaching course."
Q: "You think of becoming a coach?"
Puyol: "Maybe I’ll find a calling I never had."
Q: "Was it hasty accepting Barça’s offer of being Zubizarreta’s assistant?"
Puyol: "Yes, but I don’t regret it. I learned a lot. But I think that it wasn’t the moment, not because of the club, but because of me.
Q: "When did it become clear that it wasn’t working?"
Puyol: "On my first day in the office, I noticed that it was already weird. And when I saw that I did not feel comfortable, in November, I reported to the president that I had decided to leave. In December, I told Zubi and later what happened happened."
Q: "So you leaving wasn’t in solidarity with Zubizarreta?"
Puyol: "No, I had already made my decision."
Q: "Why did you and Zubi leave at the same time?"
Puyol: "It was because of the club. It was all prepared to be announced on January 2nd. After delaying it several times. I didn’t have any problems to explain my reasons to the people. But the day arrived and I was told that this could not be the first news of the year. Then I asked them if they were going to dismiss Zubi and they told me no."
Q: "But did they fire Zubi?"
Puyol "I didn’t like that they fired him, nor how it happened."
There's more on the source twitter.