What are the advantages  and disadvantages of drilling a pinky hole in a ball.  and does adding an index finger hole move track higher and cut down on revs

The pinky hole made it easier to hold onto the ball and took some of the pressure off of my arthritic fingers. The index finger hole raised my track a bit. I didn't measure the revs, but the ball went longer before hooking.

For me, the pinkie hole was for comfort. Now it did affect my roll, i could get around the side alot more instead of behind ball so take that into consideration but you dont always have to use the hole.

You don't always have to use the hole if you don't have an x-hole in the ball. Note you can't have two empty holes.

So i wonder then if Tom Daugherty is exempt from that. He has a thumb hole, but doesn't use it always, and an xtra hole. So if thats the case, his ball is illegal?

He uses his thumb all of the time. There's a handful of guys who are considered "no-thumb" because of their release but they actually use their thumb as a stabilizer. Even some two handed bowlers use their thumb, I believe Wesley Low is one example if I remember correctly

According to the USBC website, no mention of any 'stabilizer' thumb use.

Holes or indentations for gripping purposes shall not exceed five and shall be limited to one for each finger and one for the thumb, all for the same hand.  The player is not required to use all finger holes in any specific delivery, but they must be able to demonstrate, with the same hand, that each gripping hole can be simultaneously used for gripping purposes. Any thumb hole that is not used for gripping purposes during the delivery would be classified as a balance hole.

According to the USBC website, no mention of any 'stabilizer' thumb use.

Holes or indentations for gripping purposes shall not exceed five and shall be limited to one for each finger and one for the thumb, all for the same hand.  The player is not required to use all finger holes in any specific delivery, but they must be able to demonstrate, with the same hand, that each gripping hole can be simultaneously used for gripping purposes. Any thumb hole that is not used for gripping purposes during the delivery would be classified as a balance hole.

Interesting - I stand corrected.

I don't know Tom, but from what I've read he's what's known as a "half-thumb full roller".  He only inserts his thumb to the first joint, so it looks like he's not using it at all.  --  JohnP

JohnP- Smallwood is a full-roller and half-thumber.
Daugherty- 2finger no thumb just like the video shows. Curious if any of Daugherty's
                 equipment has weight holes.