WALTHAM, Mass. -- The film that Boston Celtics coach Brad Stevens showed his team at the start of training camp Tuesday morning had been ready to roll since mid-August, though it underwent too many revisions before and after that point to truly count.

Since the end of the 2013-14 season in mid-April, Stevens has tortured himself with film study from his team's 25-win campaign and plucked the clips he thought would best demonstrate to his players just what needs to be done this season to take the next step in a rebuilding process that can't go fast enough for anyone involved.

After months of poring over game film, Brad Stevens is happy to be back at practice, saying, "This is the fun part of my job, this is what I've always enjoyed the most -- watching the team." AP Photo/Michael Dwyer

Stevens, with a white polo tucked into green basketball shorts, beamed as he stood at center court and watched his players get loose for Tuesday's second session. Twenty-four hours earlier, he had sat a podium in the same gymnasium and apologized to reporters for any rambling answers he was giving during the team's media day because he was so focused on the first team practice that loomed.

"I've had [the film cut up] for a while. I've been bored," Stevens deadpanned Tuesday before his team's afternoon session. "I told someone the other day -- they said, 'What are you doing?' And I said, 'Paralyzing myself by analysis right now.'"

Stevens first said he took a week after the season to breathe, then took it back by admitting he cheated and studied film at nights or while traveling during that span. Even if you give him full credit for taking seven days after Boston's season ended, he's still had a mind-numbing 161 days to comb through film for answers to his team's struggles.

That's 3,864 hours to dissect the team's 57 losses. That's 231,840 minutes to wonder how so many games slipped away in the final minute.

There had to have been something better on Netflix to watch.

"It was more about analyzing what didn't go right and figuring out what we could control to make that go better," said Stevens.

There's a renewed confidence in his voice, not that his ever wavered last season. Even from day one of his surprise hiring, Stevens met everything thrown at him head-on during his first NBA season and battled through when the losses piled up.

But you get the sense that he's even more prepared for his sophomore campaign. That he's hell-bent on avoiding the pitfalls that tripped up his team last season, and that he yearns only to put his team in position to win more often.

Stevens gushed with optimism about his team's potential last week at a charity golf tournament. Despite his best attempts to avoid jinxing his team (knocking on wood when the injury subject came up), he woke up Friday to learn his best player -- All-Star point guard Rajon Rondo -- broke a bone in his left hand and would miss as much as the first 10 weeks of the season.