WALTHAM, Mass. -- One of the themes that Boston Celtics coach Brad Stevens has repeated in the days leading up to the start of training camp is just how slim the margin was between Boston being a lottery team and a playoff combatant last season. Stevens has noted that the Celtics, despite all their second-half success that propelled the team to the seventh seed in the Eastern Conference, still finished as close to 12th overall as they did to fourth.

So maybe it's no surprise that, one day after his players gushed about lofty goals, with some like Avery Bradley going so far as to wonder why Boston couldn't be a championship-caliber contender, that Stevens started training camp by reaffirming that narrow line his team must still navigate.

As he's done in years past, Stevens showed his players a mashup of clips -- snippets of film from around the league that most resonated with him while showcasing what the Celtics must do to move forward and not slip back. While slim on specifics about the film session, Stevens noted, "We reflected quite often that we were as close to 12th as we were to fourth and showed some of the little things that go into winning and losing."

Even a newcomer like David Lee thought the message was pretty clear.

“I was amazed. The amount of details was the biggest thing," said Lee. "[Stevens is] a numbers guy, a technical guy as you probably well know. He showed us a lot of stats in there of where the team can get better than last year and how thin the line is between the fourth or fifth seed in the East or being 12th and missing the playoffs. So he did a really good job of illustrating those things and telling us, defensively, we need to be where we were last year or get even better. And, offensively, there’s a few categories we can get better at to improve that efficiency. So I think it’s good for players to know Day 1 what needs to be accomplished, and then you work every day to get there."

With the road map to where they want to be laid out before them, the Celtics then engaged in a light, untaped 90-minute morning session. Things will ramp up at an evening workout in which the team will engage in more contact activities with the goal of starting the process of determining exactly how the team's lineups and rotations will look when the regular season arrives in a month's time.

Those lineups will be a source of constant chatter during camp (and, heck, it was hard for reporters not to start taking note of jersey combinations, even after what amounted to a walkthrough practice to start camp). While Stevens has stressed not to get too worked up about early combinations, he admits he's constantly rolling it around in his brain as well.

"In my mind? Two months ago. On the court? We’ll find out," Stevens said when asked when he'll start thinking about lineup combos. "I’m not going to rush it. I’d like to have an initial rotation by the time we play in Milan. But that will change by the time we play our first [regular-season] game."

Five more highlights from Saturday's first practice of training camp:

• Sully on first session: After his tale of basketball intervention was maybe the biggest story from Friday's media day, Jared Sullinger was asked how his body responded to resuming team activities. "Really easy, actually... Getting up and down. It was better than John Lucas, I’ll tell you that much," Sullinger said of the former NBA coach that led him through a summer grind. Sullinger also confirmed that he hopes to be more of a post presence this season. "Take the open shot when I have it but, at the same time, make an emphasis to getting my big butt on the block and move some people around," he said.

• Green lights for Young: Coaching associate/Director of Player Development Kenny Graves had a new sideline setup where players activate lights while dribbling to improve their ballhandling skills. Second-year guard James Young gave the media a glimpse of it in action on Saturday. (Watch HERE)

• Breaking the glass: Stevens on getting back to work: "I think the first day is the first day. [The second session], when we do more competitive stuff, we’ll probably break some of these [office] windows [nearby] and throw the ball all over the gym -- that’s just the way it goes. We used to always tell our people in our first college practice, ‘Don’t sit within 10 rows because you’re going to get hit by a ball.’ You turn it over a lot early; that’s the way it goes. We’re building day by day. We still have a long way to go. As far as comfort and how we want to do things, I think we got a general feel, but that will be largely determined by who ends up on the court."

• Get some rest, rook: Guard Terry Rozier, Boston's top pick in June's draft, said the first workout was light on contact, but the team still got up and down the floor a bunch with Stevens emphasizing the heightened pace that the team prefers to play at. Rozier still had a hop in his step after the first session and said he heeded some veteran advice before Saturday's first session. "I heard a lot of people say, ‘Get some rest, rook.’ So that’s what I tried to do. I went to go see a movie and I was asleep by 11:30 [on Friday night]. I got a decent amount of sleep."

• A championship comparison: Asked his impressions about how Stevens addressed the team at the start of the season, Lee offered high praise in return. “It was very similar to [Golden State Warriors coach] Steve Kerr last year, actually," said Lee. "They have a lot of similarities. They’re very positive. They’re teachers on the floor. It’s important to be a teacher with the amount of young guys we have, but all the little details are very important to him. And those details are the things that win basketball games." And what sort of details did Stevens stress on Day 1? "I just think continuing to move the ball, player movement. And also diving to the hole a little bit more versus taking long contested 2s is something he mentioned today. You hear that a lot, a lot of the theories today in offensive basketball is to take a 3 or a good open shot, or score in the paint. So he talked about the number of contested 2-pointers they shot last year and how that, if you take a few of those out and you replace them with layups or finishes in the paint, or 3-pointers, how that can change the efficiency of the offense."