I get asked a lot why second-year Charlotte Bobcats big man Bismack Biyombo is getting inconsistent minutes this season.

Sometimes the simple answer is also the most accurate one: Inconsistent performance causes inconsistent minutes.

Biyombo played well in as a fill-in starter Friday, totaling 13 rebounds and three shots blocked against the New Orleans Hornets. After that game coach Mike Dunlap said Biyombo earned a bigger “bite of the apple’’ in terms of minutes.

So Saturday, with veteran center Brendan Haywood back from a family emergency, Biyombo played 10 minutes off the bench in the first half against the Dallas Mavericks. He contributed one rebound, one block and no points. Dunlap didn’t play him in the second half.

I can’t fault Dunlap for that decision. The positive signals Biyombo sent in New Orleans were negated by the negative ones he sent versus the Mavs. And that’s OK: Yes, he was the No. 7 pick in 2011. But he’s 20 years old and arrived in the NBA from Africa, by way of the Spanish league, with minimal basketball background.

You know who understands that? Biyombo. I spoke with him at Tuesday-morning shootaround about his minutes and role. Last season he was a starter as a rookie. This season he’s a reserve. Rather than complain, he takes this as a challenge.

“I’ve got to get my game to the level it’s supposed to be,’’ Biyombo said.

What must improve?

“Everything – try to help the team as much as I can in the time coach is giving me,’’ Biyombo replied. “What I do is rebound and block shots. We’re trying to add little things.’’

Biyombo arrived in Charlotte with so little offensive game that then-assistant coach Rob Werdann literally taught him how to correctly catch the ball. He’s a bit more polished now, with the occasional jump hook or five-foot jump shot. But Hakeem Olajuwon, he’s not.

So Biyombo has to have big impact at the defensive end to be a factor. Byron Mullens told me Dunlap’s defensive system is different from predecessor Paul Silas’ in that power forwards have to switch a lot more, taking brief stints guarding perimeter players outside the lane. Under Silas, there wasn’t as much difference between how a center defended and how a power forward did.

That works for Mullens, who has really good footwork for a 7-footer. It’s more difficult for Biyombo, whose comfort zone is close to the basket. So it seems wise to keep him at center, rather than dabble at power forward.

“It is a little bit different,’’ Biyombo said of Dunlap’s approach versus that of Silas. “Not different as far as looking at the game, but you do have to adjust. We’re always asked to switch in some kind of situation, especially at the end of a game. So far I think we’re doing good.’’

Biyombo isn’t a bust. He also isn’t under-utilized. He’s a work-in-progress.