I think it's likely the minimum the Jazz can give in an extension is 7.5% less than he's making this season. The FAQ is poorly written/worded, and doesn't explicitly rule out the remaining years on a contract being amended. This downward amending doesn't really make sense though. If the 7.5% decrease is the rule, Al's salary next season could be no less than $13.875mm in an extension. Too much.
#59 also, indirectly, clears this up, stating that player salaries can't be amended downward in contract renegotiations.
Are you mixing amending and extending or am I missing something? Player's Union has been efective in eliminating amendments from anything other than pay increases. Extensions don't fall under this though. #59 covers renegotiations only, and a extension is not a renegotiation.