My reasoning was based on Sanchez playing mostly on the right and occasionally centrally. They are obviously given the freedom to shuffle around in the final third, but Jesus seems to be much more effective centrally and I think that Pep has recognised this. Sterling, who can really only play on the right, will get some game time. As will Bernardo, who some people seem to have forgotten about. Considering all of this, we can conclude that Jesus, Sergio and Sanchez will be competing for the central position, with all three competing with Bernardo and Sterling out right. That's a lot of competition and, even when considering the number of games, I think it extremely likely that Sergio will receive significantly less game time than both Jesus and Sanchez.
The one position where we really don't have a lot of competition is out left, where Sane appears to be undroppable given his performances. Whilst Sanchez could possibly play there, I don't think that he could in Pep's system, where the wide players are asked to stay out wide during the buildup. It will be interesting to see if Bernardo can play there.