First off my throwing arm anatomy ain't the way it was when i was born it has been surgically altered and there is residual stuff pressing the nerves so it might influence my experiences some.
Iacas have you seen the Dave's tips video on Innova main page where he talks of the thumb determining the grip strength? You should watch that video.
I always say to try out hings for yourself to test your beliefs. iacas used the words: "I believe". Some tests are extremely easy to perform.
Test one: Strip your forearm bare and hold out your arm straight in front of yourself as far away from the body as you can pointing each finger straight forward. Looking at the forearm muscles on both sides of the largest bones of the forearm move the thumb from pointing straight forward to pointing 90 degrees away from forward left or right depending on which side you're looking at (palm up or down). You should see the muscles move. Movement of the muscle indicates that the muscle is not at rest any more. Forearm muscles are at rest when the fingers point forward. Not when the thumb points away from straight forward. The farther to the side the thumb is pointed the tighter the forearm muscles get. A tight muscle is a slow muscle.
Correct me if i'm wrong but i saw an episode of Sports Science where they said that there are just tendons in the hand and the fingers move by those tendons being pulled by the muscles in the forearm. I need to ask a physiotherapy student i know of that but we won't see until later. I haven't studied anatomy.
Iacas pointed out a great thing about the form of golfers using 3/10 power (feel but how high a percentage of available power actually?) and still getting a strong grip that allows for freedom of movement of the wrists and whatnot. That is what disc golfers need too to a point -staying loose at some parts of the throw to have good wrist mobility while doing the work of accelerating the disc. In the elbow straightening phase the acceleration tries to make the wrist bend back. If it is resisted so that the tendons stretch the wrist will snap forward when the arm starts to move left to right rotationally. From the tendons returning to the normal length. At that point you can utilize a loosely moving wrist to actively add to the snap by using consciously guided active muscle turn of the wrist to the right of neutral. That is the second time there is a good idea to have looseness. The first is in getting the arm to accelerate quickly so depending on the person it might be the right pec area, earlier or later.
Test number two: Setting the thumb in front of the index finger and pushing down with the thumb allowing a free range of movement to the rear of the disc what happens? A free range of movement needs the rear of the disc to rise above the seam of the hand so the base of the thumb can't be in the way. This way it is possible to raise the rear of the disc above the inner joint of the thumb.
Popping up from the grip is possible. Which is the more powerful grip? The one with 4 or 5 fingers? The farther you throw the higher the demands are for the grip strength. Maybe you have not yet overpowered your grip with the power you generate elsewhere. When you do it is easy to see why a more powerful grip is needed to add distance. Anyone can experiment with the limitations grip strength puts on the distance.
Test three: Greasing or soaping up the disc will quickly show the difference between the amount of fingers on the disc. And the orientation of the thumb in the regular or Jenkins way.
So far the strongest grip i've had before trying the pictured way except with the index finger too over the disc has come from a hybrid grip. The thumb is in the Jenkins orientation but the base of the thumb is on the disc. In freezing temperatures it is very easy to see the difference the addition of the Jenkins orientation makes. Also laying the base of the thumb and pushing it down on the flight plate against the pinky pushing up. Without those tricks i get early let slips often with slicker plastics. I've never been able to throw as slick discs into as low temps as this year thanks to the grip modification. I suspect and it feels like the Wiggins grip with the index finger on either side of the disc will add to the grip strength so it will be interesting to soo how it works in action. So far i've tried it only indoors.
Iacas is right about the arm pull geometry influencing the time and manner in which the thumb slides off of the top of the disc. The thumb is the last part on top of the disc to slide off of the disc so that time determines how long the disc can pivot between the fingers even partially. The thumb sliding on the disc won't give the perfect efficiency to the pivot like a static thumb to flight plate position contact would give. The length of the disc pivot limits the power generation. I'm not the only one who has tested that they get longer flights from moving the thumb somewhat toward the center of the disc delaying when the thumb slides off of the top of the disc. The thumb slips off before the index finger does. After that i don't think there is anything added to the speed and spin of the disc. Unless someone has way more index finger power than i do.
Being injured and not monster strong with possible subconscious protection of the arm i might have compromised ability to clamp down the thumb long enough to get an optimal disc pivot. Slo mo video suggests that. That might not be a problem for everyone but i can't usually meet the minimum required thumb pressure to get as late a rip point on the edge of the disc from the thumb at full power as i can get with an approach throw. At low power i can throw the disc backwards pivoting around the arm launching to the right and back from the back of the hand side. No joy at full power. Also the taller and wider winged the disc the less i can pivot it. So at least for some adequate thumb pressure generation is an issue with normal grips. I'm itching to know if this grip would solve that for me
Too bad there's a lot of snow on the ground now.
Test four: See which grip yields the most distance. Thumb not on top of the disc, thumb lightly touching the flight plate and thumb pushing down as hard as you can. Then you know how close to the minimum required thumb down pressure you have relative to which distance you get your disc to fly. It would be great to have excess pinch strength. masterbeato wrote that you need to clamp down hard late in the throw and he's pushing 700'.
My grip strength requirements have changed as i've gained distance. If someone has excess gripping power that person might not see a difference as their distance increases. Then there's the issue of detection accuracy and the ways you explore things. One person might detect differences and another one not. So it is not the clinic holders only that vary also the students and their research methods and experience varies too. Once you've felt a new thing it is easier to detect later and with enough practice a previously undetectable thing can become a no brainer.
Flat shots need running on the center line of the tee and planting each step on the center line. Anhyzer needs running from rear right to front left with the plant step hitting the ground to the left of the line you're running on. Hyzer is the mirror of that.