Just a little more info for clarification.  The only time you can pre-bowl is the weekend.  We are one of the fortunate houses that have leagues every night of the week that take up 80-100% of the house.  House policy is to only run lanes used by leagues plus 1 pair.  And they do not re-oil on the weekend.  Most weekends, the house is 75% full of open play.

So depending when you pre-bowl, your lanes haven't been oiled in 1 to 2 days and you're following lots of open bowling left overs.  So your scores will suck.  So most pre-bowl score are 30-50 pins lower per bowler.  80% of the bowlers in the league average 170-220.

So yes teams would send someone to watch because they knew the scores were like 100-200 pins below team averages on pre-bowl and you can get that that in 7-8 frames and then play "the game" and still win 4.

We're also talking a league that runs 35-60 hdcp brackets a week where if someone is all in, and they bowl a bad game 1 and lose them all, game 2 and 3 will be terrible when their teammates who aren't in brackets bowl great.  We had to institute a 10 pins rule in brackets the first 7 weeks.  If your average is 10 or more pins below your book, you bowl off your book in brackets.  When you have a 205 bowler averaging 170 after 9 games and he magically wants in all brackets when he didn't enter the 1st 3 weeks. 

It's all about making money.