The underlying theory of Russball is to reduce the time that the other side have the ball to score by holding the ball. Since that if we try to score we would end up losing the ball, we wouldn’t encourage our players to try to score.
In fact we have some decent PL level players McCathy (if not playing Rusball), Sulemana, Tall Paul, Alcaraz. But Martin doesn’t use them because they don’t fit in his system.
But he will continue his system at all costs.