There's really only two main rules I follow when trying to get lined up in tournaments.

1)If it's a longer pattern I grab pin up balls
2)If it's a shorter pattern then the pin under balls come out.

The pin up balls i.e., pin over bridge, or pin over middle finger for me, have quicker cycle times in the hook to roll phase of the "skid, hook, roll" method of describing ball roll.

Pin down balls have slower and smoother transition times (cycles) and are better when there's a lot of friction to navigate through at the back of the pattern.

On a true flooded pattern it is true all balls pretty much work the same but the right drilling with help those who can find the pocket.  A 6" pin to PaP distance is the ideal for playing a flood shot.  You're not trying to stray away from the pocket and you need the core to ge into a roll.  The 6" ptp cycles the quickest once it sees friction, it won't cover too many boards, but it will stand up and provide optimal cycle time and carry.  

If you can ever see what some pros are throwing on the Cheetah pattern there's two schools of thought.
The pin down/under bridge or under middle finger in order to maximize the cycle time of the core.  The surface is adjusted in order to get to the pocket, the core optimizes the carry.
The other thought is pin up drillings past 5" pin to pap in order to get the ball to stand up early and hook out into the pocket still retaining energy to carry. Chris Barnes has used this method on several occasions when playing straight on TV.  It looks like he is trying to make the bal roll out, when he's trying to get the ball to hook out with a quick cycle drilling while allowing the ball to retain enough energy with a weaker shell to carry well.

It's these seemingly backward traits of specialized drillings that allow many on tour and higher average bowlers in general to average the 250's and 260's for a tournament.  It doesn't happen at every tournament but it's the lucky one that finds the right match of coverstock to get to the pocket and the right drilling to carry everything.

And of course all of this is from my experience as a higher rev player.  Take these museings with a caveat as the quick or slow cycle times may not be as visible with slower rev rates.  Denny Torgensons articles in BTM address these issues of building an arsenal as well as the brunswickinsiders.com website.  Rick Benoit has excellent write ups of tournaments and includes pics and blurbs about the balls and the drilings he chose for that week all outlining the slow or quick cycle response to friction.

Everyone aggrees the coverstock is the most important factor of a ball.  Without the right cover and right cover preperation you won't be able to hit the pocket.  Once the pocket is found carry needs to be addressed and this is done with drilling.

Just like a car.  A car has to have the right kind of tires (coverstock) in order to move.  Those tires can't work correctly without the right engine (core).  And that engine can only push the car so far without the right transmission (Mass Bias).  But that's another musing.


*Backswing
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*...Got the 5 out clean!

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