Drake Powell drives to the basket during the Nets' July 10 game in Las Vegas. NBAE via Getty Images

LAS VEGAS — Drake Powell’s shooting slump is part mental, part mechanical and entirely maddening.

It’s always unwise to put too much stock in rookie summer league performances.

But as a second-year pro, the defensive-minded Powell was expected to take a step forward offensively.

Instead, the young Nets guard has sunk deeper into a funk.