bottom line, you can thrown a bunch of strikes any 14 15 16 lb ball!!!

practice helps also fyi!!!  HEHE

Couple other factors to be considered here is that some pros are moving back to 16 due to the fact that it will push down through the pattern more and creates more and more consistent friction.

Also, according to recent studies by Kegel the heavier the ball the less influence lane topography will have. And if you think that USBC testing verifies that your house is within spec then you need to look into the study Kegel has done.
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ALL STAR BOWLING & TROPHY
LANGAN'S ALL STAR LANES
WALLED LAKE MI

I used to think there wasn't much difference.  Now I'm not so sure.

I started with 15lb back in 2004.  Had some injury issues that seemed to be bowling related, so I dropped to 14lb and they went away.

I never was a high average bowler, but I used to pride myself on my accuracy.  Never got many strikes, but I chalked that up to being wrong about the pocket (being between 1 and 3 instead of hitting 1 pin first).  

Anyways, this year just seemed like I was overpowering the ball....and my accuracy was crap.  I was pulling the ball and throwing too fast.  I had to make a conscious effort to slow down so that didn't overshoot the break point.  

One of my teammates bought a couple of new balls during the season and the topic of ball weight came up.  He was surprised that me and another teammate were throwing 14  (one teammate has the same span and was using one of my old balls and didn't even know what the weight was).  Said we should be "men" and throw at least 15.  Had the discussion that weight isn't that big of a deal, as long as you can control it and hit the pocket.  

I guess it kind of bothered me a bit, so I plugged up a 15lb that I had picked up here and decided to take it in one week.  I figured I'd throw it during practice, see if it messed up my timing and see if my injury came back.

That was week 31 of a 35 week season.  Well, each week I managed to raise my average a full pin.  I went from getting mostly 8 and 9 counts, and maybe 2 strikes a game, to probably averaging 6 strikes a game.  I used to leave a ton of corner pins, 4 pins, and occasional splits (4-9).  

Maybe it was the ball change?  I don't feel like I threw the ball any better.  I played the same basic line as before.  I still had the occasional tug, and I didn't change spare balls (still 14lb).  Since I was already working to keep my speed down, I don't feel that I lost any speed or revs by moving up. I just seemed to get better carry with the 15lb ball.

Of course, my tennis elbow seems to have come back, but I think that was starting to act up before I made the switch......and it doesn't bother me when I bowl.  Either way, leagues are over now.  I guess if it clears up I can blame it on the ball, but I'm confident I'll be using 15lb at the start of next season!

Sorry for the novel, that's just my experience.

I switched from 16 to 15 about 1 1/2 years ago.  I found that my game improved (had my 2 personal high series in that time).  15s seemed to be just right for my strength level while 16s felt too heavy once I actually made the comparison.  I could do more things (i.e. it felt easier to put more revs on the ball).  16 is probably preferable, but if it is too heavy, then going down will probably result in better shot making.

Appx. 70% of the players on the PBA tour use 15lb. equipment. That being said, there are many who still throw 16lbs.-----Walter Ray Williams, Jr., Norm Duke, Parker Bohn III, Chris Barnes, Brian Voss, Robert Smith, etc.

If the lanes are oily and/or tight 16lbs. will carry better that 15lbs. or 14lbs. When bowling against brand new pins 16lbs. will carry better.

On most other conditions 15lbs. will carry as well as 16lbs.-----maybe better due to 16lbs. hitting too hard.

The only way i can see 14lbs. carrying consistently as well as 15lbs. or 16lbs. is by someone who can create greater angles of entry------even then I'm not sold.