MELBOURNE has received an explanation from the AFL's umpiring department about the five free kicks paid against star big man Max Gawn for ruck infringements against St Kilda on Sunday.

The Demons were surprised at the number of free kicks paid against Gawn, with coach Simon Goodwin saying after his side's 24-point win over St Kilda the club would contact AFL umpires coach Hayden Kennedy for clarification.

Gawn was left mystified after conceding the free kicks to Saints opponent Billy Longer and even cheekily tweeted a picture of the AFL's Laws of the Game booklet, with the caption "some light reading this week".

However, Kennedy told AFL.com.au that Gawn's use of a "straight arm" block to keep Longer from contesting the ruck was the major reason the Demon was penalised so heavily.

"Basically, both players have to have the ability to contest the ball. If there is a straight arm by one of the players, when the other player is contesting the footy, that's when it becomes a free kick," Kennedy said.

"We haven't been paying many of them at all. If you go through the stats, there might have been one a game.

"There hasn't been any particular focus on it. It just so happened that in this particular game there was a little bit more evidence for the umpire."

Kennedy said the centre-square ruck free kicks were generally tough to determine for an umpire, although in this case he said the umpire became more aware of Gawn infringing. 

"They're difficult ones for the umpire to pick up, especially in the centre because if you imagine what's happened, they've bounced the ball and they've backed out so they're only a small distance away from the play," Kennedy said.

After the win over the Saints, Gawn expressed his bemusement at the spate of free kicks paid against him. 

"I gave away free kicks that I've never given away in my life. I don't know why they were free kicks but they kept on blowing the whistle, so I was getting a bit frustrated," Gawn told ABC radio after the game. 

"I ended up having to let Billy Longer just win them in the end, because I didn't know what to do."  

Gawn is set to renew hostilities with former Demons teammate and Brisbane Lions counterpart Stefan Martin when the teams do battle at the MCG on Sunday, as Melbourne continues its bid to end an 11-year finals drought.