Originally Posted by pvaudio
Poly is designed to and does generate more spin than Kevlar. It is why Kevlar is more or less obsolete: poly does absolutely everything better. Pros who used to use Kevlar are now using poly for this reason.
Poly does not do everything better. Poly can never compare to the consistent control of kevlar, never especially after a few hours or days. Pro players change their string jobs every ball change which is around a half hour or so.
So us amateur players that use a string job for much longer will not enjoy the magic of poly that only lasts for a hour or two.