3 Players Who Still Have to Step Up for the Boston Celtics

Optimism surrounding the Boston Celtics is on the rise following a rocky start to the 2016-17 NBA season.

Buoyed by the returns of Al Horford (concussion) and Jae Crowder (ankle) to the starting five, the Celtics (8-6) have won their last two road games, climbing back into the Eastern Conference's top half. 

When active, Horford (14.8 PPG, 6.6 RPG, 4.8 APG, 2.4 BPG) has been the lineup's main stabilizing presence. The Celtics are 4-1 when he suits up, and the All-Star also has a 14.8 net rating in his 158 minutes of action. Fellow core pieces Isaiah Thomas (26.4 PPG) and Avery Bradley (team-leading 6.6 RPG) have also carried heavy burdens during the team's uneven and injury-riddled start.

The bigger problem head coach Brad Stevens faces now is handling an underperforming supporting cast. Here are three players he needs more from if the Celtics plan on challenging for the No. 2 seed in the East.

Amir Johnson

Jonathan Bachman/Getty Images

Amir Johnson has been a fixture in the starting lineup since he was signed to a two-year, $24 million contract last July. The 6'9" big man is a steady defensive presence when paired with Horford most nights, but his inability to end those possessions with rebounds is a worrisome issue for Boston.

Johnson, 30, is averaging just 6.6 rebounds per 36 minutes, the lowest number of his career since becoming a full-time player. That's also a dramatic decline from his production last season, when he grabbed 10.1 boards per 36 minutes.

The problem is even worse on the defensive glass for the 11-year veteran. He is corralling just 12 percent of all available defensive rebounds, a sharp dip from last year's mark (19.6 percent). Through 14 games, Boston is the worst defensive rebounding team in the league, and Johnson's decline in that area is a big reason why.

The Celtics are already undersized in the frontcourt with Horford (6'10"), so they can't afford to pair him with one of the league's worst rebounding bigs.

"We got to get better at [rebounding], and we've got to get more consistent finishing each play," Stevens explained. "There are going to be times where we are all going to be flying around and aren't going to get the ball. We just have to make those the rebounds we give up. Not the ones where we miss a block-out or choose not to pursue for whatever reason."

Johnson's rebounding isn't the only area that's seen a decline, however. He's shooting a career-low 54.2 percent from the field and has scored in double digits in just three of 14 games.

If he can't step up his scoring or production on the glass, he may find himself coming off the bench before too long.

Gerald Green

Brian Babineau/Getty Images

When the Celtics brought Gerald Green into the fold this summer, they were gambling that he could once again become an offensive spark plug off the bench after a down year with the Miami Heat.

"I've been a big Gerald Green fan because I've been scared of him," Stevens said in September. "And I think that that's a great way to figure out how good a player is. When you go into a game, he's on your scouting report, maybe in a highlighted way because he could go off for a lot of points in a short amount of time.

"He can change the course of a game. Does he do it every night, historically? No. But he's had moments and times where he has done that. So I think he brings a spurt ability to us that we clearly needed from a scoring standpoint."

The nine-year veteran has failed to live up to that lofty praise through his first 14 games in green. In fact, he's been one of the worst offensive players on the roster to date, averaging a career-low 4.1 points per game and shooting a team-worst 31.9 percent from the field.

Part of the slow start can be blamed on a hip pointer that limited Green during the preseason, but his subpar performance in Miami (8.9 PPG, 39.2% FG, 32.3% 3PT) is looking less like a fluke by the day for the 30-year-old.

The swingman has also struggled with defense throughout his career, and that trend has continued in Boston. He has the worst defensive rating (111) of the team's backcourt. That number and his shooting woes have pushed him out of the rotation.

The 6'7" wing will likely get another chance at regular minutes down the line, but he'll need to prove he's a net positive on offense once more to make up for his defensive shortcomings.  

Kelly Olynyk

Brian Babineau/Getty Images

For his first three pro seasons, the Celtics were a better team when Kelly Olynyk was on the court. That trend has not continued in the 7-footer's first eight games this year.

The 25-year-old made a late season debut on Nov. 9 after a lengthy recovery from offseason shoulder surgery, and he's been slow to regain his scoring touch.

Olynyk is averaging a career-low 7.5 points per contest while shooting just 39.3 percent from the field and a team-worst 28.6 percent from three-point range. He's also averaging a mere 1.9 free throws per 36 minutes, a sign he's still shying away from contact around the basket. Those lackluster averages have been a drag on the offense, as the Celtics sport a 99.3 offensive rating with him on the floor, a sharp drop-off from the team's 108.5 points per 100 possessions when he's on the bench.

That dramatic split has forced Stevens to reduce Olynyk's playing time in the past three games (he hasn't logged over 20 minutes since Nov. 16).

With his defensive averages (0.1 BPG, 0.1 SPG) also on the decline, Olynyk has not helped his cause during a critical contract year. The Celtics expect him to be a stabilizing force for the team's second unit, and he needs to do more on both ends of the floor to live up to that label.

Unless otherwise noted, statistics are accurate through Nov. 22 and are courtesy of NBA.com and Basketball-Reference.com. All quotes obtained firsthand unless otherwise noted.