Nowitzki had his streak of 11 consecutive All-Star appearances snapped last season, when he missed 29 games because of arthroscopic knee surgery. But Cuban considers the down season to be an aberration, citing Nowitzki's injury and the Mavs' subpar point guard play.
"If there's one missing piece between what everyone is saying and what we're doing, everybody, I think, has dismissed Dirk -- like Dirk is done and he's on the downside and he can't play anymore and he's not the type of contributor that he was," Cuban said during an appearance on ESPN Dallas 103.3 FM's Galloway and Company.
"If you look at the mess that we had in terms of our guard play and basketball IQ, when Dirk came back and really got into gear, we beat a lot of good teams. I think we were at a 48- or 50-win clip. You put a much better set of players around him, and Dirk is in a situation where he doesn't have to rush back. He's had all summer to prepare his body and get ready."
Nowitzki averaged 17.3 points per game last season -- his lowest since his rookie season in 1998-99 -- and the Mavericks failed to make the playoffs for the first time since 1999-2000. But Cuban went as far as to say that Nowitzki still is an MVP-caliber player.
"Knock on wood, if we stay healthy, I think people are just missing Dirk in ways they shouldn't," Cuban said. "Like I've been telling him, Karl Malone won an MVP at 35 and there's no reason why he can't be considered in an MVP conversation at 35.
"I can also tell you, the way people are just randomly dismissing him as being done has been incredible motivation for him as well."
The 7-foot Nowitzki, who never had missed more than nine games in a season before last season, averaged 18.9 points and 7.7 rebounds after the All-Star break, shooting 50.5 percent from the floor and 43.3 percent from 3-point range during that stretch. The Mavs went 18-12 after the break, which projects to a 49-win pace for a full season.
Nowitzki, the 2006-07 MVP and 2011 NBA Finals MVP, has averaged 22.6 points per game during his 15-year career.
The Mavs believe Nowitzki is still capable of putting up those kind of numbers if paired with a savvy, pass-first point guard, which is why they signed Jose Calderon to a four-year, $29 million deal.
"Look, the missing piece is everybody is dismissing Dirk," Cuban said. "Everybody thinks Dirk is done. Maybe he can't put up 30 a night. Maybe he's not going to go for 50 when he wants to. He's not going to have those Dirk vs. Tracy McGrady-type battles, but he's still going to demand a double-team. He's still going to be a guy we can go to get a bucket at the end of a game. Dirk is still going to be a guy that will get you buckets when you need them.
"Now, we've added someone who can run a pick-and-roll with him and knows how to run it and knows how to use a screen."
Nowitzki is entering the final season of a four-year, $80 million contract, but he has committed to re-sign with the Mavs next summer at a drastically reduced salary.
After missing out on Dwight Howard this summer, the Mavs will continue trying to acquire a superstar to complement Nowitzki, with Calderon and high-scoring free-agent addition Monta Ellis headlining the supporting cast.
Cuban is adamant, however, that Nowitzki remains a superstar.
"Maybe Dirk won't win an MVP," Cuban said. "But trust me, Dirk can still play."