The three biggest takeaways from the Sixers' preseason loss to the Celtics

The Philadelphia 76ers had a tough night at TD Garden on Saturday as they lost 139-89 to the Boston Celtics in a preseason game. However, considering the circumstances of Philadelphia resting its core roster while Boston fielded most of its starting roster that had won a title in June, the outcome was predictable.

The Sixers got 20 points from rookie Jared McCain, while KJ Martin and Justin Edwards each scored nine points and Guerschon Yabusele added eight points and three rebounds. Philadelphia received some encouraging performances from some young pieces.

Here are the three biggest takeaways from the loss in Boston:

Jared McCain's NBA education

McCain certainly got a taste of what it's like in the NBA. The Celtics went right at him, while proven stars Jaylen Brown and Jrue Holiday went right at him at times. He also struggled to shoot the ball from deep (1-for-8) as Boston made the rookie uncomfortable on offense.

It wasn't a great performance for McCain, but the rookie didn't shy away from the challenges the Celtics gave him. He continued to compete and fight, getting some great finishes at the basket and battling on the glass. He went right at Derrick White, who is one of the better perimeter defenders in the NBA, and had some nice finishes in front of and around him. This competition was a great experience for him to continue his early NBA education and familiarize himself with what is happening in this league.

Guerschon Yabusele at 5th

It will be interesting to see how long Yabusele continues to receive minutes at the center spot. While his offensive game can make a difference on that side due to his shooting ability and soft touch around the basket, he simply doesn't have the size to make a difference on defense. The Celtics got into the game easily and big man Luke Kornet found plenty of easy baskets at the rim. As the pre-season continues, it will be something to watch as coach Nick Nurse works through his new squad.

KJ Martin's audition for a rotation spot

Martin is only 6-foot-1, but his defensive acumen and athleticism make him play much larger than his height. He scored nine points on 4-for-7 shooting with four rebounds on Saturday and showed off some of his basketball IQ by finding spots around the basket and getting out in transition. Defensively, there are some issues for him due to his lack of size, but he makes up for it with quick hands and the ability to be in the right spots to harass opponents.

This article originally appeared on Sixers Wire: The three biggest takeaways from the Sixers' preseason loss to the Celtics