Think of it this way, when you are bowling hundreds of games each month, 1 extra pound is a lot of extra pressure on your wrist, arm and shoulder. In the past the heavier equipment carried better. But with the balls today, a 15lb ball will carry just as well as a 16lb ball. And on the drier conditions, as imnutzo mentioned, you can throw it a little harder.
I currently use 16 lb equipment, and still average about 19 mph. I be afraid to see what it would be with 15 lb balls.
--------------------
Jorge300
"Some time, when the crew is up against it, and the breaks are beating the boys, tell 'em to get out there and give it all they've got. And win just one for the Zipper. I don't know where I'll be then Doc, he said. But I won't smell too good, that's for sure."