PAUL Roos and Nathan Buckley briefed their players in the lead-up to their games last Sunday after noticing "a clear difference" in the way round 17 matches were being umpired.

The Melbourne-St Kilda clash drew 54 free kicks – the most of the round – and 16 of those were for holding the ball.

Roos said he had spoken to his playing group ahead of the match, but expressed his discontent that clubs were not advised of stricter rule interpretations.

"I actually spoke to our players before they ran on to the ground … I'd watched enough football on the weekend to know that the rules had changed for the weekend," Roos told Fox Footy on Monday night.

"The disappointing thing for everyone is that we weren't told going into the weekend.

"There was a clear difference … (but) I didn't think it was going to be as dramatic, as confusing and as frustrating for all."

Buckley echoed Roos' point of view, citing the lack of communication from the League's umpiring department to clubs over the course of the week.

"The umpiring clearly shifted from the first two or three weeks when everything's fresh … we dropped away from actually adjudicating the rules as they were and we've seen a sudden spike back," Buckley said.

"There was a clear shift in it and there was no communication to the clubs. I spoke to our players as well.

"The reason the weekend stood out was because it was so different to the weekend before."

Earlier on Monday, AFL umpires boss Wayne Campbell said he was surprised at the "spike" in free kicks on the weekend and admitted the League's officials went overboard on advice to look for more infringements.

There was an average of 45.4 free kicks paid in the nine games in round 17, up by nearly 10 from the previous round.

The umpires had been coached last week to look for infringements in marking contests, pushes in the back and 50m penalties, but Campbell said some miscommunication had seen the umpires take things further in what he called "a hiccup".

"We've been coaching the last couple of weeks to try to find two or three missed free kicks," he said.

"We certainly didn't expect the spike that occurred on the weekend. We didn't want it to go from the number it was to the number it got to in the end."

Clubs have already complained to the umpires' department about the over-officiating across the round, and Campbell said the AFL would have informed the clubs of a change in umpiring mentality had it been aware it would be so significant.

"We'd like to think that since [umpires coach] Hayden (Kennedy) and I started we've been very transparent with clubs, and any time we've made any sort of adjustment no matter how subtle it was, we've actually told them," Campbell said.

"On the weekend we saw it umpired a little differently to what it was the previous week and we weren't expecting that spike.

"It was a little surprise to us as well, and so therefore we weren't able to tell the clubs because we didn't see the spike coming."

Free kicks are slightly up on last year overall, with an average of 36 paid each game in 2015 compared to 33.4 last season.

The significant jump across round 17 attracted criticism and brought confusion, but Campbell said there had been no instruction to pay more free kicks to encourage a more free-flowing game style. 

"Clearly if you pay more free kicks it opens the game up, but there's been no direction from anywhere that we have to pay a certain amount of free kicks or we have to pay more free kicks," he said.

"We as an umpiring department thought that we were missing two or three free kicks and we want to be consistent and get to that level where the public know what is a free kick and what's not."

Campbell supported the decision to award a free kick against Richmond star Dustin Martin for spraying water on a Fremantle opponent, but acknowledged the uncertainty around the rules for ruck contests after several puzzling frees were paid over the weekend.

"In general the philosophy is that we want both rucks to be able to get an even chance at the ball. And secondly, it's not an easy area to adjudicate especially around the ground with third-man up and things like that," Campbell said.  

AVERAGE FREE KICKS PAID PER GAME 

2006 33.6
2007 38.4
2008 40.8
2009 36.0
2010 38.8
2011 40.4
2012 37.8
2013 36.2
2014 33.4
2015 36.0           

2015 BY ROUND         

Round 1 40.8
Round 2 39.2
Round 3 36.8
Round 4 38.0
Round 5 41.2
Round 6 33.2
Round 7 32.2
Round 8 35.4
Round 9 34.6
Round 10 32.4
Round 11 32.2
Round 12 34.6
Round 13 33.8
Round 14 30.2
Round 15 35.2
Round 16 36.4
Round 17 45.4