I've been collecting complete TAB Bookmaker data on the line market since 2012, and the average expected victory margin this week - 12.9 points per game - is the lowest it's been for any home and away round during that period.

There were no changes to the Top 3 teams on MoSSBODS or MoSHBODS this week, the first ranking change for MoSSBODS occurring at position 4, now occupied by GWS, and the first for MoSHBODS occurring at position 6, now occupied by Essendon after a four-spot climb.

The MoS twins had excellent Round 17s, MoSSBODS_Marg returning a competition-best 8 from 9 amongst the Head-to-Head Tipsters and the second-best mean absolute error (MAE) amongst the Margin Predictors, behind only MoSHBODS_Marg's 21.3 points per game.

Despite last week's average Total score of almost 190 points per game, our four forecasters are back this week suggesting that the average for Round 17 will be about 10 points per game lower.

The two RSMP forecasters took 1st and 2nd places on the Head-to-Head Tipster and Margin Predictor Leaderboards last weekend, in the latter case displacing MoSHBODS_Marg after an 8-week unbroken stint in the top position. 

Port Adelaide's victory over West Coast was just comprehensive enough, in Scoring Shot terms, relative to Sydney's win over the Gold Coast to see Port reclaim top spot on MoSSBODS.

This week, it turns out, one of the best ways of tipping winners would've been to glance at the pre-round competition ladder, as seven of the eight winners started the round ahead of the teams they eventually defeated.

This week the four forecasters foresee lower average scores, reflecting recent history which has seen average Totals fall below 179 points per game in every round since Round 7. Last week's average of 168.1 points per game was the second-lowest of the season, above only the 165.3 points per game in Round 13.

Normally, at this point in the season, some semblance of an order emerges and you feel as though most games in most rounds will adhere to a familiar script. Sure there'll be the odd fluffed line and lighting mishap, but the play will be performed largely as written. This year, it's all improv, all the time.

In a season that will surely be remembered for its unpredictability, how apt it is that MoSSBODS should finish the weekend with Sydney, very narrowly, as its number 1 team.

It was, as we predicted, a fairly unpredictable round, with only two favourites emerging victorious and another snatching a draw.

Yet again this week, the Lions are playing in the only game of the round expected to top the 200 total and yet again they're expected to register only about 40% of that total.

If every contest in a 9-game round was essentially a coin toss, the chance of correctly tipping all nine winners would be 511/1. This weekend, based on the bookmaker's mid-week odds, the chance is only about one-eighth of that or about 68/1. Those are the longest odds we've seen for picking the card all season, ahead of the 55/1 for Round 1 and the 40/1 for Round 4. (The shortest for any of the 9-game rounds by the way was 18/1 for Round 3).

Port Adelaide now sits atop the MoSSBODS Combined Ratings and has moved into 3rd on MoSHBODS on the backend of a 31-point and 11 scoring shot victory over Collingwood. The Pies fell three places on MoSSBODS and two places on MoSHBODS based on that same result.

In a season as unpredictable as 2017 has been, you have to be pleased when your head-to-head tipsters average 6.4 from 9 and your margin predictors produce an average mean absolute error (MAE) of 24.8 points per game.

This week it's the Lions v Giants game that's expected to crack the 200 total according to all four forecasters, with the Giants projected to score about 60% of that total.

The first three games of the heavily-abridged Round 13 look too close to call this week, which has made for some of the highest levels of Head-to-Head Tipster disagreement we've seen this season.

According to MoSSBODS and MoSHBODS, Port Adelaide didn't do enough in defeating the Brisbane Lions by 40 points and 10 Scoring Shots over the weekend, and so shed Rating Points (RPs) on both Systems. As a result, they slipped to 3rd on Combined Ratings.

Only three of the round's six favourites were successful this week, and none of the MoS Head-to-Head Tipsters did better than BKB's score of three.

MoSSBODS and MoSHBODS both think we'll see over 200 points in Saturday's Port Adelaide v Brisbane Lions game, though they differ in the proportions of those points that they expect the two teams to record.