Kepa has been frozen out at Stamford Bridge with Tuchel preferring Edouard Mendy as his first-choice but the Chelsea boss believes his team's difficulties in front of goal -- with 13 goals in his 12 games as head coach -- are in part down to the role played by his own goalkeepers.
"For Kepa I'm pretty sure it is a disappointment not to be selected," Tuchel said. "That is clear but like I said before, he is super strong here. He is our player. It does not influence how we work with him, how we trust him, if we trust him.
"This is also a personal goal to be in the squad of Spain. Would it be easier if he played on a regular basis? Yes. Clearly, yes. But it is not about his personal objective, it is about Chelsea. We have said the communication straight between our goalkeepers that Edu is the number one and he is competitor for that.
"He has to be ready and I can just say he is exactly doing this. He is 100% reliable, top guy, top goalkeeping, top performance in training together with [third-choice] Willy Caballero. This is outstanding. This, by the way, does not help our strikers because it is so super hard to score in training because of our goalkeepers and then we end up maybe with Timo Werner."
Werner has endured by his own admission the toughest spell of his career, scoring only two goals in his last 26 games across all competitions following his £47.6m move from RB Leipzig last summer.
The 25-year-old's barren run has led to speculation he could seek a return to Germany but Tuchel cited an upturn in recent performances -- most obviously impressing in Chelsea's 1-0 win at champions Liverpool earlier this month -- as evidence he is happy at the club.
"For Timo, I think he has no reason now to be frustrated because he did an amazing match against Liverpool, maybe his best match since I arrived. Then he had a good match against Everton with a lot of chances to score which he is normally clinical enough and strong enough. He did not score, OK.
"In a situation like this, this can affect his self-confidence of course. The clear advice from us is 'don't focus on the result, focus on the process, get your decision-making right, get your technique right, take good decisions, for the decisions take the right technique and the ball and the opponents goalkeeper will do the rest. Then it is in or he does an amazing save. He can improve from there.
"But there is simply no time on what is going to be in the summer, next year and the next year. There us simply no time. At the moment, I don't see why he should be frustrated. We gave him a little bit of time to breathe against Leeds.
"It was hard for him to come on and he was not too much involved in the last 20 minutes because it was not our best game. But right now, I don't see why he should be too frustrated. And honestly, nobody here is blaming the strikers. It is a team effort to attack and a team effort to defend.
"We expect our guys to create more chances, to be more decisive. In the end, it is my responsibility to put them in the right mindset, the right positions, to let them play regular and from there on we go. Maybe all the stuff that you read will hopefully disappear soon."