Suárez, Alves and Neymar have been the most explicit when they didn't like to be substituted
A sample of the high competition that exists in Barça's first team squad is the rage of some players when they have been subbed-off. In the last 2 games, this has been evident in the cases of Dani Alves (against Manchester City) and Suarez (against Granada). In their own way, both players have shown their hot blood and made explicit that they don't like to be subbed.
The feeling of wanting to play every minute is normal in football. What generates more questions is whether this demonstration must be made public or should remain in the dressing room. Some players are not playing as minutes as they would like; this is the case of Pedro, Xavi or Ter Stegen. They also explained they would like to play more, but without externalizing this feeling in the middle of a match.
The public demonstration of the fact that one is not sharing a coach's decision depends on every player. Warm-blooded players are more likely to show it publicly. The clearest cases this season are those of Luis Suárez, Neymar and Dani Alves. Here you can watch videos where they showed their rage after being substituted.