Reggie Jackson is rapidly rounding out his game.

But there's one thing still missing.

A reliable 3-point shot.

As the Thunder point guard prepares for his third NBA season, strengthening that skill will be one of Jackson's main goals this summer.

It certainly will be the most important one.

Jackson made just 23.1 percent of his 3-pointers this season, ranking last among players with at least 100 attempts.

Serge Ibaka made a higher percentage.

Shoot, Ronnie Brewer made a higher percentage.

So you know Jackson struggled from beyond the arc. It was a weakness that lingered as the biggest hole in Jackson's game and stood out for the wrong reasons in what was an otherwise fantastic season of growth.

“He still needs to continue to improve and he will,” said Thunder coach Scott Brooks. “He's a guy that loves the gym. He's going to have another big summer of improvement. We'll be with him step by step in that improvement.”

As a rookie, Jackson suffered through the same shooting struggles, connecting on only 21 percent from 3-point range. And there was only minimal improvement this season.

Jackson made four of seven 3-pointers in November but then went 4-for-26 in December and January. He started off February on the right foot, making four of 11 in the month's first five games, but then shot 20 percent in the season's final 31 contests.

In the postseason, Jackson was either scorching hot or ice cold. For instance, he made 34.5 percent of his 3s in six games against Houston then dipped to 21.4 percent in five games against Memphis.

Teammates think Jackson is bound to improve because of his resolve and relentless work ethic.

“Reggie is often times one of the first few guys in the building every morning, putting in that extra time that it takes to be good and to be great,” said Thunder guard Derek Fisher.

That, of course, is what Jackson since day one candidly has said he wants to be — great.

“I think the great ones, that's what they do, offensively, defensively, always in attack mode, always in a fight,” Jackson said. “Whether others follow or not, they just bring their best every day and that's the kind of mentality I believe you have to have. I'll just try to keep that in the back of my mind; stay hungry, humble, just work on always being in attack mode, whether it be in pickup games (or) workouts getting ready for next season.”