Lou:
Yup, that's my point about snooker players -- when you hear snookies say "cue action" -- it's kind of a misnomer, because they also mean everything to go along with the actual stroking/action of the cue, including the PSR, bridge length, etc.. As you know, I use (and am a big advocate of) the superiority of the snooker way of looking at mechanics. They look at everything -- not only the alignment of the joints/parts of the body -- but also including the orientation of the grain of wood in the cue, so as to reproduce "expectable" results. With today's laminated / radially-consistent pool shafts, that's not necessary. But *if* (key operative word) he's using plain maple, he probably has the shaft marked to put the "backbone" or "keel" of the quarter-sawn maple wood on top (with ash, you'd see chevrons at this keel-marker in the wood), to produce what would probably be expected to be the same amount of deflection in the left/right direction.
It's not just about the grain. To say "otherwise there'd probably be much more variation in his bridge length" is over-simplifying what goes on in the snooker PSR. It's not "pick and choose" -- rather, they do it all.
HTH,
-Sean