From my experience with old tables it’s a combination of issues, first off, as cloth gets older it makes the pockets less forgiving. Another issue is pocket facing angles change over time if a good mechanic doesn’t stay on top of it. The subrail portion of the facing gets hammered with balls hit with force and some of that energy is not fully absorbed by the facing rubber. Over time the wood behind the facing becomes mushroomed, or distorted. Once distorted it loses its original correct reference angle, and the overall decline snowballs when an inexperienced mechanic changes the cushions without correcting the subrail angle first. So keep the bangers off the table, or if you can’t do that then hire a good mechanic who will keep those facing angles at the proper angles.