THEY SAY THEY'VE heard about it, but haven't experienced it. They've been told it really does exist, but they're not ready to accept the premise. This is the annual discussion of whether there really is an NBA rookie wall.

"I heard a lot about it, but it's hard to say what it is," the 76ers' Jason Smith said.

"I don't know what it is," teammate Thaddeus Young said. "I haven't actually hit it yet. I don't think so."

As the Sixers revel in Saturday night's dramatic, 99-97 victory in Memphis and look ahead to Wednesday night's game against Miami in the Wachovia Center, it would seem that Smith, the 7-foot forward/center, has hit the supposedly mythic wall more than Young, the 6-8 wing man.

Smith, who showed a nice midrange touch earlier in the season, has shot just 12-for-32 over 91 minutes of the last seven games, 5-for-20 in the last five games; in a four-game stretch from Dec. 12 to 19, he took just six rebounds in 56 minutes.

"It may be that he just missed shots," Sixers coach Maurice Cheeks said. "He's at a different level now; you have to kind of realize that. He's got to play a few more games [in this league]."

Unlike a college schedule, Cheeks said, "We're nonstop. We travel, we play. It's not all about [how many] minutes you play; in college, they practice more than they play.

"[The coaches] were talking about, this [27 games to date] being a full college season. It's normal for [the rookies] to be kind of winding down, but now they're going to continue to play. They've been playing throughout the summer and through the preseason. This is a lot of games for them."

Smith, the No. 20 pick in June, said he has dealt with "bumps and bruises, nothing you can't overcome, though."

"You can go out and have a great game one night, then a couple of bad games," he said. "You've got to keep competing throughout the season. My shot's been struggling the whole season; I've been up and down. I need to get more consistency with that."

He's still figuring out the pro regimen, a constant diet of practice, play, travel.

"Definitely," Smith said. "It's something I've got to get used to. I haven't gotten used to it yet . . . It's just a different lifestyle for me. It's definitely a different daily schedule; you're traveling all the time, playing games all the time. You really have to get your rest, take care of your body."

Did somebody say rest? That's a factor that has become more prominent to Young, the No. 12 pick in June who was inserted into the regular rotation nine games ago, averaging about 13 minutes.

"They say [the rookie wall is] when you get real tired and your body can't go anymore," Young said. "I feel fine. I've been able to go. I think if I were playing 30 minutes a night, I'd probably be a little tired right now. I've heard some of the guys say they're tired, that their bodies are a little sore."

Still, when the Sixers are rewarded with a day off, as they were yesterday, Young finds himself sleeping - or at least resting - a lot.

"When we get days off, usually Sundays, I actually stay in bed until 4-5 o'clock," he said, sheepishly. "The days we get in [from the road] at 2 a.m., I kind of have a hard time falling asleep, but when I do, I get some good rest.

"If you're not playing with a lot of energy, you've definitely hit the wall. The other day, I was talking to my brother and said, 'We've got to go out of town again? We just got back.' He said, 'This is the life you're living now.' ''

Six shots

The Sixers showed what has become their trademark resilience in the victory in Memphis, winning on Andre Iguodala's 20-foot jump shot as time expired. Iguodala, who had been 2-for-12 through three quarters, scored 17 of his 23 points on 7-for-9 shooting in the fourth quarter, a terrific performance behind Andre Miller's season-high 29 points and Samuel Dalembert's 14 rebounds and three blocks . . . When Rodney Carney stepped in for Willie Green (left hip strain), the Sixers became the last team in the league to finally make a change in its starting lineup . . . The Akron Beacon Journal reported that the Cleveland Cavaliers have contacted the Sixers about Andre Miller, but Sixers president/GM Eddie Stefanski said in an e-mail response that there was "nothing there." *