Bob Thornton wasn't budging even though Marc Gasol, at 7-foot-1 and 265 pounds, is awfully good at making people budge. But each time Gasol banged into Thornton on the low block, Thornton banged back, his chest and belly offering as much resistance against the Memphis Grizzlies' center as possible.

This went on time and again, about an hour before the Grizzlies' preseason game at Chicago Tuesday night. It was like a pair of powerful, bighorn rams fighting for turf and supremacy, except in basketball post-up position, back to belly. After Gasol, it was Zach Randolph's turn.

By the time they all retreated to the locker room, a game still to be played, Thornton -- twice Gasol's age, Memphis' assistant coach with responsibility for the team's big men -- was breathing harder and sweating more than either Gasol or Randolph would against the Bulls that night.

Thornton is 6-10 and weighs a little more than his playing weight of 225, but that's a good thing when he's pushing back as an on-court teacher. So is the fact that he played professionally for 11 seasons, including eight in the NBA with five different teams. He walked in their size 16 Nikes and they know it.

"It helps a lot," Thornton said later that evening. "There are little nuance things you can take advantage of. Defensively, offensively. 'If a guy's guarding you this way, look at this, because he's definitely overplaying you. He's not paying attention and we can do this...'

"Last year in the playoffs when Zach was getting crowded, we showed him some clips. We said, 'You need to drive more. You need to rip through and attack more.' And it worked. He got to the foul line more."

Look around the NBA. That sort of bump-and-grind action goes on all over the league in warm-ups and on practice courts. Past "bigs" work with current bigs, sharing experiences, handing down tricks of their outsized trade. Many assistant coaches are recognizable as centers and power forwards who played in the league -- Bob McAdoo, Jack Sikma, Herb Williams, Popeye Jones, Ed Pinckney, Joe Wolf, Marc Iavaroni, Thornton.

Now look around again: How many head coaches are big guys? Right. Of the 20 current coaches who played in the league, only one -- Houston's Kevin McHale -- was a classic NBA big (and a Hall of Famer at that). In recent memory, Bill Cartwright, Kurt Rambis, Iavaroni and a few others have held the top job but the list stll is short.

Consider the NBA Coach of the Year award, which has been presented 50 times since it was created in 1962-63. Other than Phil Jackson (1995-96), who played power forward for New York and New Jersey, you have to go back to Johnny "Red" Kerr (1966-67), Dolph Schayes (1965-66) and Alex Hannum (1963-64) to find bigs chosen as their profession's best in a given season.

Generally, NBA teams have been more comfortable with short guys coaching bigs than vice versa.

Nazr Mohammed has been with eight clubs in 15 seasons and has spent practice sessions with coaches of various sizes. "Some teams have used big guys but you also have a coach like Larry Brown, who was very hands-on with his big men," Mohammed said. "[Gregg] Popovich is like that also -- [former Spurs assistant] Don Newman did a lot of the work with the big men, but Popovich was hands-on.

"In Charlotte it was LaSalle Thompson, it was Charles Oakley for a year. I've had different guys. It comes down to the philosophies of the head coach."

From whom and precisely how current players learn that stuff -- whether it comes from five feet above the court or seven -- shouldn't really matter. But there is something about peer-to-former peer instruction.

"It's just because you can relate to what they're talking about," Thornton said. "The feel. The look. The physicality. Just little things that I know as a big. I'll talk to our guards but sometimes I qualify it by saying, 'I never played the position, but this is what I see...' I think you have to do that."

Marc Gasol believes it helps that he can see eye-to-eye, literally, with the person doing the specific, intensive position work. "Big men know there are different things you have to look at. Having a guy who really understands that -- preferably a guy who has played there -- it helps, particularly with the younger guys to make the transition easier. They've been through already what you're going through."

For years, big men have developed their games in the offseason, attending Pete Newell's famous big-man camp or working individually. Some NBA legends -- Olajuwon, Kareem Abdul-Jabbar, Bill Walton -- are sought by players and their employers as summer tutors (Olajuwon has been especially in demand lately).

Still, you don't see them getting recruited as coaches. Abdul-Jabbar has been frustrated by the lack of opportunities. Patrick Ewing interviewed in Charlotte and Portland over the summer but came up empty, turning down the Knicks' pitch to coach their NBA D-League entry in Erie, Pa. Miami's Pat Riley has touted McAdoo as a coach for years to no avail.

Kim Hughes, a former assistant with the Clippers, will coach Portland's big men this season.

"Just because you've got a big guy on your staff, to say he should only coach the big guys, that's short-changing what he can do," Milwaukee's Scott Skiles said. "If you can coach, you can coach. I don't really like the whole, 'You work with the bigs, we'll work with these.'

"Joe [Wolf], for us, when we separate and go bigs at one end, shorter guys at the other, he takes that end. But if Joe wants to go talk to Brandon [Jennings] about something, he's a coach on this team as well."

People frequently cite the old "point guard as coach on the floor" saying about basketball as a reason so many smaller men get hired. Also, it's a math thing: The pool of average-sized job candidates -- former NBA players or just terrific lifetime coaches -- is far bigger than the relative puddle of tall guys.

Then again, there might be a stereotype in play.

"Definitely, from our view, it's harder for a big man to become a head coach," said the Bulls' 6-foot-10 Mohammed. "The perception is, 'the big dumb guy.' I'm not saying it's true. It's a perception. 'The big, dumb, clumsy big man, how's he gonna coach?' But we've had some great ones. Dave Cowens. Paul Silas. Phil Jackson!

"So there have been some who've succeeded. But it's definitely harder, because they think you can only coach big men. You've got to prove you can coach the guards. You've got to prove that you have defensive schemes, and you know what the guards can do and the forwards need to do on defense."

Said Thornton, who would love a shot after years as a scout, assistant and coach in the D-League and CBA: "A lot of former guards are getting jobs, which is fine. But we have a unique perspective because we see the whole floor from inside-out. Guards see it from outside-in. It's just a little bit of a different perspective, but it doesn't mean that we can't coach guards.

"It's like being a catcher. We see the whole floor, we see everything develop. We can direct and make things happen. So it's just about communication."

If there is a misperception at work with NBA general managers -- a glass ceiling about 78 inches above the court -- it's not surprising to the league's former centers and power forwards. They learned long ago to duck their heads.

Steve Aschburner has written about the NBA since 1980. You can e-mail him here and follow him on Twitter.

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