Very frequently, many players with great technical movement manifest confidence issues because of the inconsistency of their strokes. They are convinced that this lack of consistency is a technical problem: that you must hit more in front, a better position, with more topspin, etc.
While these may be factors that need to be adjusted, they are almost never the main reason. Personally, I find that the main reason a player is NOT being consistent is because they are trying to hit beyond their own technical skills baggage. This means that they try to play based on how they would like, or were told to play, and not really on how they can really play.
I like to consider each shot as "entities" of the player. Each player has "one" forehand, "one" backhand, "one" serve, etc. and somehow, they have their own "personality". The shots speak. With each mistake or success, they tell us what we did well or what to adjust, but the player very rarely listens, not because they are deaf, but because they have not learned to listen, as we (coaches) have not taught them, or because they are only listening to their expectations.
From my point of view, WE ARE ALL CONSISTENT. Everyone is capable of putting 100 balls ... but at the right level. Being consistent is not a technical problem, being consistent is a decision, therefore it is tactical. Having a more or less developed technique should only determine the decision of how I am going to try to hit the ball in. The big problem is that many times the strokes are taught and trained in complete disconnection from the tactical decision, disconnected from the player's feelings, and worst of all, disconnected from the IDENTITY of the player. There are too many players with almost perfect movements but who cannot hit the ball with a certain intention. They are the players with a technique "implanted" artificially from the form and not from the sensations: turn, stand, hit, finish, or any of the 10,000 different progressions that exist. It is useless to teach a preparation or a finish if you do not look at the ball and decide when and how to hit it according to the feeling. The technique has to be developed respecting each stage of development in which the movement is and that each step forward is from the player's internal feeling of FEELING ABLE, that is, from the CONFIDENCE.
The consistency problem is very easy to solve, it can be achieved in 15 minutes, it is just necessary to change the point of view of the decision of the shot, accept what the shot is, identify the real level it has and at what speed it is RELIABLE. It is easy to solve, but many times, the difficult thing is for the player to accept that at this moment he/she is not the player who thinks and that he must "slow down" to connect the real technical level with the tactical decision that this technique allows. The incredible thing, the "magic" is that, if you do, if you accept your reality, the shot will accommodate, will adjust, will find its zone of reliability, and almost unintentionally, will improve. If that happens, the player has taken his first step in learning to listen to his/her shots.