lil...."hanging" in the thumbhole can be caused by too many reasons to mention.  I'll list a few.
1.  wrong span(combined with wrong thumb pitches)
2.  away pitch on thumbhole combined with early turn of the hand
3.  oval thumbhole combined with early turn of the hand
4.  squeezing the ball (wrong span or holding the ball weight with your thumb
     instead of fingers)
5.  broken wrist at release point
6.  really late release point
7.  grip powder
8,  soft plastic insert
and on and on

1.  excessive body fluid (combined with salty intake)
2.  heat
3.  humidity
4.  excessive sweating
5.  stress (life and bowling)
and on and on.

Anyhow, good luck
 

Most thumb problems are caused by the wrong pitch. In my experience, the only way to find this is by trying different pitches. I know of no sure way to get the proper pitch except by trying different pitches. Maybe someone on this site knows a better way.

Lots of possibilities.  Beer drinking definitely will increase the size of your thumb.  The other one may be that when you arrive at the center your hands would be cold (thumb has shrunk) but after throwing a few balls and warming up your body temperature increases causing your thumb to swell.
Just drill a big thumb hole and drop in some tape.  I typically have 4-5 slices of tape in the front of my hole as I like the feel as well as the option of being able to take some out for when I do swell.

lil...."hanging" in the thumbhole can be caused by too many reasons to mention.  I'll list a few.
1.  wrong span(combined with wrong thumb pitches)
2.  away pitch on thumbhole combined with early turn of the hand
3.  oval thumbhole combined with early turn of the hand
4.  squeezing the ball (wrong span or holding the ball weight with your thumb
     instead of fingers)
5.  broken wrist at release point
6.  really late release point
7.  grip powder
8,  soft plastic insert
and on and on

1.  excessive body fluid (combined with salty intake)
2.  heat
3.  humidity
4.  excessive sweating
5.  stress (life and bowling)
and on and on.

Anyhow, good luck

This is a long comment so I will address it separately lol. Ill try to hit everything in my reply

1. My span is correct. I am 99% sure anyway. I was recently remeasured due to some pain issues I was having and my span had lengthened from when I was first measured about 5 years ago, and I have not had any pain since. The hanging up is a reoccurring issue from even before then.
2. Pitches I am not sure on... I have wanted to play with thumb pitches, but never have. I do not believe I turn the ball early either. I do not feel like I turn the ball much at all. I try to just let it roll off my hand. I need to take a video soon,
3. I use a round thumb hole. After I get away from the switch grip, I am going to go with a normal thumb slug and oval thumb. Doing that on the next ball I buy.
4. I am not squeezing the ball. I consciously make a point to not do this. If i accidentally do, i know it and the result is obvious lol
5. No broken wrist
6. dont believe the release is late, except for the ball hanging up causing it to be later. when i can keep the swelling down and get my thumb out when i want it out, the ball rolls out onto the lane nice and early. I like to roll the ball into the lane rather than onto the lane if that makes sense
7. I think you make have hit the nail on the head with this one, but it is the crux of the situation. I never even thought of this. I have sweaty hands. like really sweaty when i bowl. for years i have used one of the grip ball things to dry my hand off before each shot. I may try to go without it tonight and see what happens.


now for the rest of the comments.
I don't drink beer. I don't like beer. I do like sweeter and fruity alcoholic drinks (don't judge me lol) though and i do drink on one of my leagues. haven't noticed a difference on the nights i drink and don't drink. I do not exactly have the best eating habits so sometimes I do eat a lot of salty foods, but it isn't consistent. Hell, i have days where I do not even eat all day before league and my hands are still swollen. I might be able to deal with that if getting rid of the rosin bag stops my thumb from sticking.

I don't know my pitches, measurements, or anything of the sort. But if not using the bag does not solve the issue, I'll change something on the next ball I get drilled. I'm really wanting to drill up a venom cobra

Hey I forgot to give my results after league Sunday. I went the whole night without even looking at a rosin bag. I didn't have many hanging up issues. There were just a couple times I did, but that was more because of the swelling issues and MAYBE moisture on my thumb, but it was much improved over recently. I think it has been compounded issues all coming together for one bad situation.

Rosin causes your hand to swell.  Use either hand conditioner powder or easy slide.

Wanted to check back in. I decided I really wanted something to cover my thumb. I ran into sweaty hands because of the heat in a bowling alley I was at. As my hand dried, it became tacky. I was really sick of dealing with it. I ordered in a Brunswick glove with thumb saver combo thing. Anyway, I had league tonight and didn't want to bowl without something, so I picked up a cheap golf glove to use tonight. Cut the middle and ring finger off half way down and reamed out one of my undersized thumb inserts to use. I think I'm onto something now. I'm not going to say I got out of the ball as clean as I like, but the release off my thumb was consistent as long as Dummy #1 kept his thumb relaxed. The glove had just enough tack that I didn't feel like I needed to use any muscle to hold the ball on my hand in the back swing. I don't have to have a huge thumb hole to compensate for swelling now because I think the glove will hide some of that. Now this was just one night, but I should have done this a long time ago.