To echo what Metron said, it's not all that hard to average 200+ these days.
The balls will hook a ridiculous amount, allowing even weak players to throw a pretty strong strike ball.
The oil patterns for leagues are set up for high scoring. More oil in the middle, and it gets less and less as you go to the outside of the lane.
Result: Say you throw a decent hook ball, and through practice you've determined that hitting the 3rd arrow on the lane, letting the ball slide out to about even with the 2nd arrow then hooking back towards the strike pocket is your optimal shot.
Okay, let's say you miss a bit and get the ball too far out....there's less oil, so it'll hook a bit harder and get back to the pocket anway.
Now let's say you pull your shot, and miss to the left of the 3rd arrow. (right handed bowler)
No problem, there's a lot more oil there, so your ball will just not hook as much and get directed to the pocket that way.
Bottom line: Instead of HAVING to hit within say, 1" of your predetermined target to hit the pocket, in leagues these days all you have to do is hit within about 5 boards on the lane either way to get there. (this all assumes you threw it with more or less the same rotation and velocity)
So what you have is leagues full of guys who AVERAGE 215 and up. I averaged 215 my last year, IIRC.
IMO, this is what is hurting league bowling. Non-league bowling is as strong as ever, maybe even stronger, but leagues in some areas are hurting...and the ease of scoring is a big reason why.
Take the average 195-210 bowler, put him or her on a PBA oil condition, and they won't average 160. There really is that much difference.
Take your average PBA tournament roster and let them bowl on a league condition, and someone will shoot a 300 every single game...probably there'll be multiple 300's. It most certainly would take a 250 AVERAGE to make the finals.
There's an alternative to regular league bowling called Sport Bowling. It's still a sanctioned league, but they use PBA oil patterns.
The highest average in the country is maybe 220-ish. There were two people that high a year or so ago, but they were both from the same town, so I'm a bit suspect of that.
But it falls off drastically from there. There have been about 20 300 games shot this season in a Sport league. There have been more than that in regular leagues here, much less the whole country.
I have a friend who bowls in the Sport leagues who has won about 14 PBA regional tournaments, cashed and even led national PBA tournaments, and he averages about 208. But he rocks a 230+ in regular leagues.
If I get back into bowling, Sport is probably what I'll do....although it'll probably be pretty demoralizing to start with.