Bielsa has started Patrick Bamford over Nketiah in every Championship game this season.
This decision was brought into focus again this week when Nketiah scored a late equaliser against Preston North End.
In a lengthy explanation, Bielsa explained: "We cannot talk about Bamford when it's necessary to talk in comparison with Nketiah. I know that it's not your intention.
"But what I say about Bamford is going to be compared with what I say about Nketiah. So to talk about Patrick is more useful to describe Nketiah.
"Nketiah has developed at one club, Arsenal, and has to play at Leeds. I am not comparing the level of both. But you can see clearly the performance in one team or the other team. We don't have the players who win the match themselves.
"Big teams, like Arsenal, they have a lot of players that can win one match with one play. This is natural Nketiah has developed in this school.
"And he has all the resources, skills, to resolve the needs of scoring one goal. But we need to build the chance at goal. And we cannot build the chances if we don't have a structure within all the players to create the chances.
"You will see that every time is going to be less difficult to Eddie to be more similar to give this contribution to the team. When he in the last match went to the pitch at Preston, the match was played in the place of the pitch where he plays better, by the box.
"Against Birmingham he was far from the box and without offensive creation. And against Birmingham he didn't have a good match, against Preston he had an impact. To finish this explanation, the most important, what he does when we have to score. Nketiah is very good at scoring. Also Bamford.
"But Bamford is missing chances and Nketiah is scoring. But there is a fact before you score a goal, you build the situation that allow the chance to score.
"Bamford or Nketiah – which player do you think ran more? [Journalists answer Bamford] No, Nketiah. You know why? Bamford ran for the needs of the team. Nketiah ran just to try and score.
"The metres that Bamford ran is true to the team. And to finish, Nketiah puts these meters in to finish the action.
"It's natural. What I'm looking for, to achieve that Eddie feels the needs of the team and that he understands if he doesn't put the metres in both things, he is going to have less chances to score.
"After saying that, I am not 100% sure what I'm saying. Football is football. We are forced to analyse. We are forced to take conclusions. But if the conclusion we take analyses where we are, football would not be the first sport in the word.
"If you give him the option to chose between my way to analyse and free football, I prefer free football. I don't prefer the football I build in my mind.
"Football is of players. Be careful. Every time you find less players who deserve the freedom of the free football.