In the first season of Randolph's contract, he earned 10,666,667. Second was 12,000,000. That's 12.5%.
With regarding incentives, "The determination of whether an incentive is likely or unlikely is based on whether the criterion was achieved in the previous season. For example, if a player had seven assists per game the previous season, then an incentive based on seven assists per game would be classified as likely to be achieved, but one based on eight assists per game would be classified as not likely."
If Randolph had as little as $500,000K in incentives, the drop fits under the same 12.5% required for his raises.