Check the rack.

Check the rack.

Good idea. What we don't know from this is was this flush in the pocket, a stone 8, swisher 8, etc. Was the head pin, 5-pin, or 8-pin offset? If could be the problem.

If the answer is no to all of those,

You don't make an adjustment

This is the right adjustment to make.

BL.

If I had a dollar every time I heard that..... I would be rich, lol.  It's so frustrating to leave 2/3 stone 9 pins each game, it's so demoralizing.

For many years the solid 8 was considered the only true tap in bowling.  I believe this is still a valid statement.  The emergence of the solid 9 stems from the extreme entry angle of modern balls.  The solid 7 is often the result of a slight bad rack.  The solid 8 transcends ball technology.  I left them with hard rubber balls, polyester balls, urethane balls  and now with resin balls both 16 and 15 lbs.

Your 8s differ from the full flush hit solid 8. 

Your 8s differ from the full flush hit solid 8. 

So if a 9 is left when a ball has too steep of an entry angle, thus driving right past the 9 pin instead of hitting it, wouldn't 8 pins be left due to light hits and/or too shallow of an entry angle?

Either way, the ball doesn't hit the 5 pin correctly, which means it deflected off the head pin or just didn't get to the correct spot on the pin deck.

Of course, assuming the rack wasn't the problem.

On just about every solid 8 you see a replay of the 2 pin hits the 5 before the ball and the 5 is chopped behind the 8 instead of into it. 

Right handers, if they check the rack, usually don't look at the 2 pin or don't show much concern if the headpin is left.  But don't be the guy that reracks in league, especially a handicap league.