Why have player salaries and contracts risen so much in recent years?

1 reason is because they have gotten good in what they are doing. but if they dont do godd is will lower

A nine-year, $24-billion television deal signed by the NBA in 2014, which will cause the salary cap to rise higher than it ever has -- in money, yes, but also in sheer year-to-year growth. Last year's $70 million salary cap is expected to rise to at least $94 million; the $24 million increase is biggest leap the league has ever seen. There's no precedent for this in the NBA's history, which means nobody knows exactly what to expect from this offseason. Crazy huh ?