Valverde's time for rotations has passed after he tanked hard in CL. Now it's too late. He should have rotated for CL latter stages but failed miserably. He has zero excuses. He didn't even rest the players in easy home games.
Valverde is a rookie manager in CL, and he showed that. Zidane is leagues ahead of Valverde in mentality, which is very important in CL, some would say it's the key attribute. First season of Valverde in Europe was a disaster of epic proportions. Don't know a lot of historical data, but I don't remember us ever losing a tie after winning by 3 goals in the first leg.
Valverde has no excuses. He's been dominated in CL by teams far weaker than his. Except for the win vs Juve in the first game, almost every game Barca played in CL was mediocre. Sometimes the star players saved the day. The minute they couldn't and lady luck left us we got trashed.
The level of football required to at least push for a CL final (in terms of offensive power, team cohesion, team effort, tactics flexibility etc.) wasn't there at any point under Valverde. It probably won't ever be. It's just too much for him to handle. Tactically, physically, and mentally, we weren't even competitive enough to fight off Roma. They were very unlucky not to have scored 5-6 goals.