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During the Big Three era in Boston, summer league play had little bearing on the Celtics' season. The team was competing for titles thanks to the veteran core of Paul Pierce, Kevin Garnett and Ray Allen, and coach Doc Rivers was always wary of giving rookies and unproven players meaningful minutes. 

Now, with Pierce, KG, Allen and Rivers having left Boston over the past two offseasons, 36-year-old Brad Stevens serving as head coach and Rajon Rondo being the only remaining player from the 2008 championship squad, the 2013-14 season is surely going to be one of major change for the C's.

After the blockbuster trade of Kevin Garnett and Paul Pierce to the Brooklyn Nets, Boston's roster has plenty of clear holes that have yet to be remedied through free agency.  

With Danny Ainge opting to preserve cap space rather than pursue a fringe star like Josh Smith or Al Jefferson, this means that some of the 13 players on the Celtics' Orlando Summer League roster actually have a shot to find their way not only into training camp but potentially into some legitimate minutes for this rebuilding Boston team.

Among the notable players on the roster are 2013 draft picks Kelly Olynyk and Colton Iverson, second-year big man Fab Melo, All-SEC point guard Phil Pressey and Darius Johnson-Odom and Nolan Smith, who have spent time with the Los Angeles Lakers and Portland Trail Blazers, respectively.

Though Boston suffered a disappointing 88-95 loss to the Orlando Magic to begin their five-game stint in Orlando, there are plenty of intriguing storylines to follow as the Celtics battle for summer league supremacy with the league's new point system. 

Who Will Step Up With Nolan Smith Going Down?

Smith did not live up to the expectations of being a first-round pick in Portland, averaging 3.3 points and 1.2 assists in his 84 games before ultimately losing his minutes to Rookie of the Year Damian Lillard.

Still, as one of the few players on Boston's roster with NBA experience there were expectations that he would be one of the team's leaders and main scoring options.

Unfortunately, Smith suffered a small tear in his calf against Orlando, according to CSNNE's A. Sherrod Blakely, and played less than five minutes, scoring four points and grabbing one steal.

With Smith expected to miss the rest of Orlando Summer League, Boston is going to need somebody else to step up and provide timely scoring and facilitating in place of the Duke star, who averaged 20.6 points and 5.1 assists per game in his senior season as a Blue Devil.

Pressey and Olynyk should get bigger offensive responsibilities and more touches with Smith out, but Boston could also look elsewhere on their roster to replace his production.  

Tony Mitchell, the NBA Development League Rookie of the Year, scored 16 points and came away with three steals against Orlando, making him an option to receive a larger role.

Other options are Johnson-Odom, who looked dreadful against the Magic, missing seven of his eight shots and turning the ball over four times, and Jayson Granger, who played well in the third quarter and demonstrated solid court vision, handing out four assists in less than 22 minutes of work.

Can Kelly Olynyk Emerge as the Starting Center? 

The Celtics traded up into the lottery with the Dallas Mavericks to draft Olynyk with the 13th overall selection, hoping he could potentially emerge as an impact player for a squad that has been thin at the 5 spot since trading Kendrick Perkins in 2011.

Though there is skepticism about whether he can handle the physicality of the NBA being more of a finesse big man or whether he'll be able to rebound and defend well enough to earn consistent minutes, the early returns on Olynyk have been positive.

Against the Magic, Olynyk scored 25 points, grabbed seven rebounds and dished out two assists in just under 27 minutes on the court. While he still looks like a work in progress on the boards, Olynyk did a decent job guarding the post and, most importantly, was an absolute force on the offensive end. 

Olynyk scored consistently out of the post and even showed that he could knock down the NBA three-pointer, converting two of his four attempts. He shot just 30 percent from deep in his last year as a Bulldog, so if he can become a consistent three-point shooter that will make him an even more lethal pick-and-pop center. 

After two seasons of using Garnett as the primary center, Boston had the opportunity to pursue a quality big like Al Jefferson, Andrew Bynum or even Robin Lopez in free agency but opted not to do so. The other centers on the current roster are Iverson and Melo, so unless the Celtics want to go small by using Brandon Bass or Jared Sullinger at the 5, Olynyk has a legitimate chance to start as a rookie.

If he continues to score as efficiently as he did against Orlando, expect Stevens and Ainge to give the 22-year-old seven-footer a serious look to be a part of the starting unit. 

Can Phil Pressey Challenge for the Backup Point Guard Spot?

Pressey's decision to declare for the draft after his junior season at Missouri was surprising to many, because though he averaged 11.9 points and 7.1 assists per game in 2012-13, he shot just 37.6 percent from the floor and turned the ball over 3.5 times per game. 

Pressey went undrafted, but signed a contract with the Celtics just one day after the NBA draft, per Yahoo! Sports' Adrian Wojnarowski. Besides Rondo, Boston doesn't have any true point guards on its roster, and since the All-Star guard is coming off of an ACL injury it is essential that the Celts have a quality reserve behind him. 

In his Boston debut, Pressey put up 11 points on just five shots and dished out four assists in 19 minutes. Turnover issues continued to plague him though, as he had five in the game.

Pressey did a good job of getting into the paint and finding open teammates, but will need to take better care of the ball and prove he can knock down outside shots if he wants a roster spot in October.  

He is a capable on-ball defender who can get into passing lanes, but at times struggles to control the pace of the game and is prone to being sped-up by opponents. 

Still, with the well of free agent point guards drying up quickly and Smith out with an injury, Pressey will have ample opportunity to show if he belongs in the league.

Can Fab Melo or Colton Iverson Prove to be NBA-Ready?

One of two first-round picks by Boston in 2012, Melo was not considered anywhere near NBA-ready after two seasons at Syracuse. He appeared in just six games in a Celtics jersey, averaging 1.2 points and 0.5 boards in six minutes, spending most of the year in the D-League. 

With Boston trying to make one last run at a title, there was simply no room for an unbelievably raw  offensive player like Melo in the rotation. However, now that the Celtics are building for the future, Melo might have the opportunity to actually get out on the court and contribute, provided he can show his development during summer league.

Melo led Boston in minutes against Orlando with 28, and he managed to post nine points and eight rebounds while blocking one shot. He looked slightly better on offense than he did as a rookie, hitting a mid-range jump shot, finishing in the paint and making three of his five attempts from the charity stripe.

Colton Iverson, the 53rd overall selection by the Indiana Pacers who Boston traded for on draft night, was able to make an impact in limited playing time. He failed to score in 16 minutes, but grabbed four rebounds and kept possessions alive with his effort and ability to box out.

He does not project to be much of an offensive threat as a pro, but Iverson was a good rebounder and interior defender at Colorado State who has the size and strength to protect the post. Additionally, he provides the kind of effort and grit any team could use on their bench.

As the Celtics' summer season continues, watch for the competition to increase between Iverson and Melo, as Boston's lack of depth means that one of them has a shot to earn a role in Brad Stevens' rotation for the 2013-14 campaign.

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