Don't get me wrong, Holiday is a fine player. He has a ton of potential at 22 years old, but still managed to put up 13.5 points and 4.5 assists per game last year. Solid numbers, but not worth close to a maximum salary.
According to John Hollinger's PER stats, Holiday was the 147th most efficient offensive player in the league last year. Good for sixth on his team. Generally teams don't grant max extensions to their sixth best player, or to the 147th best player in the league.
Holiday's stats also suggest that he may have actually peaked in year three. He averaged less points, rebounds and assists per game in his third year than in his second. Even though he's young, his numbers don't suggest that he's going to get much better.
Paying a 22-year-old usually means paying for potential, but we can't be sure that Holiday has much more.
Holiday's playing style also isn't conducive to winning basketball. He's a combo guard, someone far more comfortable shooting than passing. It's borderline unacceptable to have a point guard who averages 4.5 assists per game. Even legendary ball hog Allen Iverson averaged 6 assists per game.
Ideally, most players like Holiday are used as sixth men. They generate instant offense but don't do much else. Even though Holiday plays defense, his offensive game outside of shooting isn't very developed.
Most teams don't pay sixth men maximum salaries. Even though Holiday is a starter, he's never likely to be more than a supporting piece.
Finally there's market value to consider. Louis Williams recently opted out of his contract worth $5.4 million to test free agency, and then signed a new deal with Atlanta that is likely to be worth a similar amount.
If Williams, who put up better numbers with Philly, is worth around $5.4 million, why is Holiday worth $15 million?
I really like Jrue Holiday as a player. He's someone Philly can really build with for the future. He's just not worth a maximum contract. Not even close.