Playing in the same team as Lionel Messi is too stressful for some players due to the Barcelona superstar's ambition, the 33-year-old Juan Carlos Unzue implied.
agitated Barca in the summer when he said he desires to leave.
The Argentina star has been a first-team player for Barca for almost 15 years and still the dominant force at Camp Nou.
"What has kept Messi going has been ambition, and that brings moments of stress with it,"
"He demands that he continues to be the best and as a consequence he always wants the maximum from those around him.
"It doesn't matter if this is team-mates, the coach, the physio or what, it produces great stress on some colleagues who aren't able to shoulder it."
's time as an assistant, Barca won the Champions League, Club World Cup, and two La Liga titles among other awards.
Barca have tried to fight for the European prize since that time, with Ernesto Valverde and Quique Setien falling short in their spell.
Ronald Koeman started in the summer and, while they have disappointed in La Liga, they have ensured their place in the last-16 of the Champions League.
considers Koeman has stepped into the team at the right time, saying it is more complex when expectations are high.
"Koeman I think he is managing well with Leo and with the group,"
"Entering a club when you have won titles is more complicated than when you're not winning. When we arrived with Luis Enrique, we did it at the right time, after a year in which the team had not won anything.
"That's how it is with Koeman, because he arrives at a very screwed up moment, but if he is not in a very screwed up moment, Barcelona don't make you the coach.
"Barcelona is always difficult, but if you do it in this situation I think the management is simpler, than for example in the situation that Quique Setien arrived after the titles that Valverde won."