Too many people took stock in using the cover number (absorbtion rate)to equate to ball death after minimal use. I am not a believer in about 90% of the cases. I do believe that maintaining surfaces in the 2000 and above grit levels become a huge deal in impacting reaction.  Most wood lanes surface is equivalent to about 600-800 and if i remember correctly synthetic is equivalent to 1000-1200 grit. So having a lower to higher grit friction the higher grit level will start taking on the surface of the lower grit. Even though you may clean a ball often it is effected by lane surface. Sometimes i believe the number logic on the covers turned to be somewhat a negative market plug. Other ball manufacturers have rates comparable from some rumors but have totally stayed away from promoting the rates as they see that can be negatively constrewed about performance. Have sold a lot of "one" series ball through one house and the bowlers that like them the most and use them most often are the ones who take care of their equipment the most and pay attention to their reaction noting when it changes.