I'm glad you actually did google 'calculus' , but now you've made me doubt you actually know what an idiom is as well
Making a bit less of a portion of the cap doesn't say anything, in fact even saying the percentages themselves doesn't say anything, unless you've got the entire league's payroll in your head to compare against. Saying he's a bit overpaid now and a bit less overpaid tomorrow is a lot different than saying exactly how his contract ranks now in the league and an estimate of it'll rank throughout his duration, and how that affects the cap going forward. For reference, the 17%+ he's making now hurts the Spurs less than the 13.1% he'll make in 3/4 years, as a result of the projected rookie extensions for Wemby and Castle, and Fox's new contract. I posted a breakdown of this in the salary analysis thread. Bottom line, a bit of nuance does matter if you actually want to put things in perspective, if you don't... just move along.