Evidently, good dimensional tolerances are necessary for precision by the game. Among dimensional tolerances, the tolerance of roundness (sphericity) is the most important as a tighter roundness perfections the balance and true roll of the ball.
But the precision is a combined result of the precision of the balls, the tolerances of the cloth and those of the rubber cushion rail. Balls have practically always the tightest dimensional tolerances, while the rubber rail wich is mounted with a typical tolerance of +/- 0.1 mm at the best, typically has the weakest precision. As such, tightening ball tolerances even further offers few benefits.