Since I am not an expert in this, I'll toss this out in the form of questions:
Will not accuracy (and pressure, but not necessarily at the same time) be affected by how tightly the ball is patched? Hence, what level or extent of 'tightness' is desirable?
Will not how clean the bore (add also smooth and lubricated) affect pressure and/or accuracy?
AND will not the texture/thickness of the fabric affect accuracy and pressure?
The answer is more or less yes, now for the real answers. ....