Jaren Jackson Jr., the fourth overall pick by the Memphis Grizzlies in this year's NBA Draft, won't be a shoo-in to earn an immediate spot in their rotation. Despite being a top prospect, the Grizzlies are not rushing Jackson's development.

As reported by Peter Edmiston of the Memphis Commercial Appeal, Grizzlies Executive Vice President of Basketball Operations John Hollinger said:

“I think whatever happens, we want it to happen organically, and not get ahead of ourselves, and make sure we're taking all the right steps on him, and not getting too excited and skipping ahead.”

There's a pretty good reason why the Grizzlies might not throw their prized rookie into the regular rotation. The 6'11 forward-center is just 18 years old. While he did show some promise in the Summer League (he logged in 11.2 points per game, 8.2 rebounds, 3.8 blocks, and shot 40 percent from downtown), Jackson Jr.'s body still has a lot of room to grow. His frame is not at par with NBA standards just yet.

Hollinger added:

“We don't want to put him into overtly physical matchups yet because he's 18 and his body is still filling out,” he said.

Also, big men are usually injury prone at the beginning of their career. The Grizzlies realize they have a gold mine in Jackson Jr. An injury would be a stab to the franchise who had a nightmare season last year. And from Jackson's perspective, this will give him time to add some heft to his frame and hopefully be 100 percent ready to absorb the physicality in the pros.