That's an easy one.
"The fans," Kevin Garnett said at practice on Saturday afternoon. "The fans are crazy at the Garden. Good or bad, boos and all. It's always good to be home."
On Sunday evening, the Celtics will be home for the first time this season. After one preseason game in Manchester, N.H., and another on the road at New Jersey, the C's will now take the TD Garden floor for the first time, taking on the Toronto Raptors at 6 p.m.
"It's good to finally get a real home game in the building," Garnett said. "It's always good to get back to the Garden. I'm looking forward to it."
The last time the Celtics took the Garden floor was on June 13, when they beat the Lakers in Game 5 of the NBA Finals and moved to within one victory of another championship. The Garden faithful then watched from 3,000 miles away as the C's let it all slip away in Games 6 and 7.
Now the team returns to the familiar parquet, starting its way down the road to redemption.
"It's great just to get a chance to be in front of our fans," Paul Pierce said. "They've waited [all summer] since we've been to the Finals. So it's good to be getting back home, trying to establish a place where we can try to be dominant this year, where we struggled a year ago. It would be nice to get off to a good start, even though it's just preseason."
This team is worlds apart from the one that took the floor at the Garden last time. Two of its biggest stars have whopping new contracts, a third has made leaps and bounds toward recovering from knee surgery, and a fourth has been sidelined for many months with a knee injury of his own. The bench has been retooled dramatically, with names like Delonte West, Semih Erden and a pair of centers named O'Neal thrown into the mix since the start of last summer.
The bench is the most important area for the Celtics to nurture this preseason. With all the fresh new faces in the rotation, the C's have a lot of work to do to develop stability and chemistry.
"We need two groups this year," coach Doc Rivers said. "That's one of the things I've talked about all year so far. I don't think we're going to be a seven-man rotation team. I don't think we're good enough. If we have to be that, I don't think we'll be good enough in the playoffs to win. I think we'll use ourselves up. So I think it's important to get two groups playing. I think it's very important. That's really the key to our season."
The C's are 2-0 so far this preseason, with wins over Philadelphia and New Jersey this past week. The second unit is coming together well; Erden and Davis carried the team in the opener against the Sixers, and a bench unit prevailed in a nailbiter against the Nets the following night, with Marquis Daniels hitting a game-winning jump shot.
"They look pretty good," said Jermaine O'Neal, who watched the first two games from the bench in street clothes. "The first game, they looked really really good, and the second game, they kind of took their foot off the gas a little bit. But it's still preseason, and we're working on some things, working on some different lineups. But for the most part, they're really locked in."