I would think it would be lack of concentration

spares in general
nice girls on the next lane
stupid kids ..somewhere at the bowling center... worst case... next lane

but single pin spares are really stupid average killers cause no one can argue about even a tenpin... these fellows don't make a step to the side when the ball comes ... if the stand after the throw... the ball just didn't get there

"Normal" average for me is 180 with at max two open frames
No open frames 190-210 or even higher
Bad hair day... no comment
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"Have fun and bowl well!" - Grayson


(\ /)
(x_x)
c.(')(')

I agree wit single pin spares.  There is no reason other than mental lapses why most people can't seem to hit single pins with regularity.  Myself included for the 7 and 4.  I miss those two pins an average of twice every league session.  That ends up costing about 6 - 7 pins in average over the course of the year.
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"Beer is proof that God loves us and wants us to be happy."     Ben Franklin  

Enjoy,
Bob

I also vote for missing easy spares. That will kill your average..
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My first child.. Hannah Allison Kiser born 4/30/2007... My little angel..

Mental pressure on yourself. If you think about it, missing a spare, you'll tend to "push" yourself for the next shot/frame to make up for the miss. That's extra pressure that causes you to pull/push/be off in timing/release just anything to make up for the miss.

Then mounting pressure if the next shot isn't just right. Last season on TV, you could see the mental pressure gone when one guy had lost by the 7 or 8th frame, then he would throw nothing but strikes from there on out, IMO, the pressure was off and he just bowled. Before then he was doing his dangest top make strikes knowing that's the only way he had a chance but that added pressure usually made him throw bad, timing off just about anything that messed up his game but once that was off...bingo...strikes.

To me, mental pressure brings on most of what folks believe to be the game killer....Mental Pressure.

JMO
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az guy aka: R & L Bowlers Pro
rlbowlerspro@cox.net
www.rlbowlerspro.com

I'm voting for carrydown.  Started Tuesday night league last night and it played like the lanes hadn't been stripped in a month or so.  Try to get it outside to go around it and it over hooked.  There has to be an adjustment for this but I'm still trying to find it.

the inability to repeat shots

most bowlers dont have a clue how many times they miss their target by several boards. even with the pud lane conditions those misses dont carry or miss spares.