On the one hand, I'm confused how a guy of this pedigree gets 5 years.
On the other hand, I could see an argument, from a strictly mathematical perspective, that signing guys to term before the cap increases dramatically over the next 3-5 years is a strong hedge on the performance bet.
In year 4, if the cap is $90M+ the buyout cost on his contract is only going to be $1M per year for 4 years. So, worst case scenario if the wheels fall off the wagon, the impact is fairly minimal in terms of dead cap.
Not saying I'm in favor of the signing I'm just saying it's not as bad as it appears.