How much do AFL teams’ midfields improve or decline from one year to the next? To answer that question, first we need to figure out how to measure the quality of a team’s midfield. One simple and compelling measure, used elsewhere, is to look at the ratio between a team’s inside 50s and the inside 50s of its opponents. This makes sense because the job of a team’s midfield is to get the ball inside the attacking 50m arc as many times as possible, while preventing their opponents from doing the same thing.

In the past home-and-away season, Geelong had the league’s best midfield by this measure; they managed to get the ball inside their attacking 50m arc 1.27 times for every time inside 50 they gave up to their opponents. The teams you’d expect join them up the top of the midfield ladder, with the Bulldogs in the number two spot. Languishing down the bottom were Brisbane and Essendon.

Over the period since 1998, which is the earliest season for which we have inside 50 stats, the largest year-on-year improvement in midfield performance was recorded by the 2011 Eagles, who had an inside 50 ratio of 1.22 compared to a ratio of just 0.89 in 2010. The 2016 Cats are right up there among the most improved midfields in the past couple of decades; adding Patrick Dangerfield in his Brownlow-winning year saw them go from an average midfield performance in 2015 (ratio of 0.99) to a dominant league-best performance in 2016 (1.27). The worst decline for a midfield since 1998 belongs to the 2016 Dockers, who went from an above-average performance in 2015 (1.15) to well below average in 2016 (0.85).

Midfield performance is somewhat predictable, year-to-year. Declines on the scale of the 2016 Dockers are uncommon. If we know how well a midfield performed one year, we can have a reasonable guess at how well it will perform the following year, as shown in the following chart.

The inside 50-based measure of midfield strength lines up pretty well, although not perfectly, to other measures. If we rate teams by their contested possession ratio , the ratings look pretty similar. Geelong and the Bulldogs are still at the top of the midfield table, with teams like Collingwood and Melbourne in the middle of the pack.

So what should we expect from teams’ midfields in 2017? Both Collingwood and Melbourne had roughly average midfields this year. If I had to guess how good their midfields will be next year, my first guess would be “roughly average,” but I wouldn’t be surprised if either team improved or regressed a little. I’d be surprised if any team pulled a Geelong and went from an average midfield this year to a dominant midfield next year. No one has added Patrick Dangerfield to their roster this off-season.

Yet Champion Data predict that Collingwood will have the best midfield next year, while Melbourne will have the worst. They’ve used much more sophisticated measures to calculate teams’ midfield strengths, employing a “complex formula” to compare each team’s midfielders to league average. Their measure looks at the quality of a team’s individual midfielders, as opposed to the team’s midfield as a whole. Still, it’s a surprise to hear that Melbourne, having added Jordan Lewis to its engine room, is expected to regress so dramatically in the midfield next year, while Collingwood soars in the opposite direction. Without access to CD’s data, nor the complex formula they’ve used to rate midfielders, we can’t see how well those measures line up with our simple metrics of teams’ midfield performance.

If you’d like to have a look at how your team’s midfield performance has changed over the years on our simple metrics, have a look at the table below. It shows the simple team midfield measure we’ve used in this post, for each team since 1998 for inside 50s and since 1999 for contested possessions.

Midfield quality

Team: Season: Team Season Inside 50 ratio Contested possession ratio Change in I50 ratio Change in cont. poss. ratio Collingwood 2011 1.33 1.12 0.07 0.03 Geelong 2008 1.31 1.09 0.12 0.01 Geelong 2011 1.31 1.06 0.20 0.01 Hawthorn 2015 1.30 1.01 0.12 -0.02 St Kilda 2009 1.30 1.07 0.27 0.09 Hawthorn 2012 1.29 1.05 0.04 -0.01 Essendon 2000 1.28 1.10 0.23 0.09 Geelong 2016 1.27 1.09 0.28 0.14 West Coast 2015 1.27 1.09 0.21 0.10 Adelaide 2006 1.26 1.05 0.04 0.00 Collingwood 2010 1.26 1.09 0.15 0.07 Geelong 2013 1.25 1.02 0.07 0.04 Hawthorn 2011 1.25 1.06 0.19 0.10 Port Adelaide 2014 1.24 1.03 0.15 0.04 Adelaide 2002 1.23 1.08 0.02 0.05 Brisbane 1999 1.23 1.04 0.26 0.00 Adelaide 2005 1.22 1.05 0.13 -0.03 Carlton 2000 1.22 1.07 0.20 0.04 West Coast 2011 1.22 1.07 0.32 0.10 Adelaide 2001 1.21 1.03 0.12 0.04 Brisbane 2004 1.21 1.09 0.11 0.07 Hawthorn 2008 1.21 0.98 0.08 0.01 St Kilda 2004 1.21 1.02 0.18 0.06 St Kilda 2005 1.21 1.11 0.00 0.09 Geelong 2007 1.20 1.08 0.22 0.05 Geelong 2009 1.20 1.09 -0.11 0.00 Richmond 2012 1.20 1.06 0.29 0.12 Sydney 2014 1.20 1.02 0.12 -0.03 Western Bulldogs 2016 1.20 1.11 0.10 0.10 Hawthorn 2014 1.19 1.03 0.02 0.00 Adelaide 2003 1.18 1.08 -0.04 0.01 Adelaide 2009 1.18 0.99 0.15 -0.08 Brisbane 2002 1.18 1.01 0.04 -0.02 Carlton 2001 1.18 1.09 -0.04 0.02 Geelong 2012 1.18 0.98 -0.13 -0.08 Sydney 2006 1.18 1.03 0.10 -0.01 Adelaide 1998 1.17 0.00 0.00 0.00 Collingwood 2013 1.17 1.04 0.12 -0.01 Hawthorn 2013 1.17 1.03 -0.12 -0.03 Carlton 2011 1.15 1.09 0.10 0.09 Fremantle 2015 1.15 1.07 0.02 0.00 Hawthorn 2016 1.15 0.89 -0.16 -0.12 West Coast 2012 1.15 1.02 -0.07 -0.05 Adelaide 2016 1.14 1.02 0.05 -0.05 Essendon 2001 1.14 1.02 -0.14 -0.08 Geelong 2005 1.14 1.04 0.03 0.08 St Kilda 2006 1.14 0.99 -0.08 -0.13 Brisbane 2000 1.13 0.99 -0.11 -0.06 Brisbane 2001 1.13 1.03 0.00 0.05 Essendon 2014 1.13 1.02 0.04 0.04 Fremantle 2014 1.13 1.07 0.04 0.08 GWS Giants 2016 1.13 1.09 0.18 0.14 Hawthorn 2007 1.13 0.97 0.20 0.01 St Kilda 2010 1.13 1.02 -0.17 -0.05 Sydney 2012 1.13 1.01 0.03 -0.02 Sydney 2016 1.13 1.09 0.01 0.08 West Coast 2005 1.13 1.12 0.09 0.07 Adelaide 2010 1.12 0.98 -0.06 0.00 Carlton 2012 1.12 1.04 -0.03 -0.05 Geelong 2010 1.12 1.05 -0.09 -0.04 Sydney 2015 1.12 1.01 -0.08 -0.01 Western Bulldogs 2009 1.12 1.05 0.06 0.01 Collingwood 2009 1.11 1.01 0.07 -0.01 Geelong 2004 1.11 0.96 0.10 -0.03 Melbourne 2000 1.11 0.99 0.17 0.03 Melbourne 2004 1.11 0.99 0.16 0.03 Port Adelaide 2001 1.11 1.06 0.14 0.05 Richmond 1998 1.11 0.00 0.00 0.00 St Kilda 2012 1.11 1.00 0.11 0.06 Brisbane 2003 1.10 1.03 -0.08 0.02 Geelong 2014 1.10 0.99 -0.15 -0.03 Port Adelaide 2003 1.10 1.01 0.04 -0.11 Western Bulldogs 2015 1.10 1.01 0.13 -0.01 Adelaide 2004 1.09 1.07 -0.09 -0.01 Adelaide 2015 1.09 1.07 0.04 0.03 Essendon 2013 1.09 0.98 0.07 -0.03 Fremantle 2013 1.09 0.99 0.03 -0.06 Port Adelaide 2013 1.09 0.99 0.23 0.02 Sydney 2005 1.09 1.04 0.08 0.08 Sydney 2007 1.09 1.00 -0.09 -0.03 Sydney 2011 1.09 1.02 0.06 -0.05 Sydney 2013 1.09 1.05 -0.04 0.04 Western Bulldogs 1998 1.09 0.00 0.00 0.00 West Coast 2016 1.09 1.01 -0.18 -0.08 Adelaide 2000 1.08 0.99 0.10 0.06 North Melbourne 2012 1.08 0.98 0.06 -0.03 Richmond 2013 1.08 1.07 -0.12 0.01 Richmond 2015 1.08 1.06 0.05 0.02 West Coast 2006 1.08 1.17 -0.05 0.05 Adelaide 2013 1.07 1.02 0.01 -0.08 Collingwood 2015 1.07 1.03 0.09 0.05 Melbourne 1998 1.07 0.00 0.00 0.00 St Kilda 2007 1.07 1.02 -0.07 0.03 West Coast 2007 1.07 1.11 -0.01 -0.06 Adelaide 2012 1.06 1.10 0.11 0.13 Adelaide 2014 1.06 1.04 -0.01 0.02 Collingwood 2012 1.06 1.05 -0.28 -0.07 Fremantle 2012 1.06 1.05 0.15 0.06 Hawthorn 2010 1.06 0.96 0.01 0.02 Melbourne 2016 1.06 1.04 0.23 0.04 Port Adelaide 2002 1.06 1.12 -0.05 0.06 Western Bulldogs 1999 1.06 1.08 -0.03 0.00 Western Bulldogs 2008 1.06 1.04 0.17 0.15 West Coast 2014 1.06 0.99 0.13 0.01 Adelaide 2007 1.05 1.06 -0.21 0.02 Carlton 2009 1.05 1.01 0.05 0.01 Carlton 2010 1.05 1.00 0.00 -0.01 Collingwood 2001 1.05 1.04 0.12 0.06 Collingwood 2003 1.05 1.07 0.03 0.01 Collingwood 2008 1.05 1.02 0.02 0.04 Essendon 1999 1.05 1.00 0.15 0.00 Geelong 2001 1.05 0.95 0.05 -0.05 Port Adelaide 2007 1.05 1.05 0.13 0.06 St Kilda 1999 1.05 0.99 0.14 0.00 Western Bulldogs 2010 1.05 1.06 -0.07 0.01 West Coast 2003 1.05 1.08 0.07 0.10 West Coast 2004 1.05 1.05 0.00 -0.03 Carlton 2013 1.04 1.06 -0.08 0.02 Fremantle 2006 1.04 0.97 0.11 0.00 Fremantle 2008 1.04 1.01 0.04 0.04 Hawthorn 2009 1.04 0.94 -0.17 -0.04 Sydney 2008 1.04 1.01 -0.05 0.01 Adelaide 2008 1.03 1.06 -0.02 0.00 Brisbane 2007 1.03 0.99 0.09 0.03 Carlton 1998 1.03 0.00 0.00 0.00 Collingwood 2007 1.03 0.98 0.02 -0.06 Essendon 2011 1.03 1.01 0.15 0.02 Essendon 2012 1.03 1.01 0.00 0.00 Geelong 2002 1.03 1.04 -0.02 0.08 Hawthorn 2003 1.03 0.93 0.04 -0.01 North Melbourne 2013 1.03 1.06 -0.05 0.08 Port Adelaide 2004 1.03 1.03 -0.08 0.02 Richmond 2014 1.03 1.04 -0.05 -0.02 St Kilda 2003 1.03 0.96 0.14 0.01 St Kilda 2008 1.03 0.98 -0.04 -0.03 Sydney 1999 1.03 1.04 0.02 0.00 Sydney 2002 1.03 0.92 0.02 -0.08 Sydney 2010 1.03 1.07 0.10 0.06 Western Bulldogs 2005 1.03 0.90 0.11 -0.10 Brisbane 2008 1.02 0.96 -0.01 -0.03 Carlton 1999 1.02 1.03 -0.01 0.00 Collingwood 2002 1.02 1.06 -0.03 0.03 Essendon 2003 1.02 1.02 0.02 0.02 North Melbourne 2011 1.02 1.01 0.08 0.04 Port Adelaide 2015 1.02 0.99 -0.22 -0.05 Collingwood 2006 1.01 1.04 0.14 0.08 Geelong 2003 1.01 0.99 -0.02 -0.04 North Melbourne 2016 1.01 1.02 0.04 -0.01 Melbourne 2002 1.01 0.96 0.08 0.01 Port Adelaide 1998 1.01 0.00 0.00 0.00 Richmond 2005 1.01 1.10 0.16 0.11 Sydney 1998 1.01 0.00 0.00 0.00 Sydney 2001 1.01 0.99 0.07 0.06 Sydney 2003 1.01 0.94 -0.02 0.02 Sydney 2004 1.01 0.96 0.00 0.02 Western Bulldogs 2006 1.01 0.89 -0.02 -0.01 West Coast 1999 1.01 0.96 0.08 0.00 Brisbane 2009 1.00 0.97 -0.03 0.01 Carlton 2008 1.00 1.00 0.10 0.03 Collingwood 2016 1.00 1.03 -0.07 0.00 Essendon 2002 1.00 1.00 -0.14 -0.02 Fremantle 2007 1.00 0.96 -0.04 -0.01 Geelong 1998 1.00 0.00 0.00 0.00 North Melbourne 1998 1.00 0.00 0.00 0.00 North Melbourne 2000 1.00 1.02 0.06 -0.01 North Melbourne 2007 1.00 1.05 0.06 0.06 Port Adelaide 2016 1.00 0.97 -0.02 -0.02 Geelong 2000 0.99 1.00 0.03 0.02 Geelong 2015 0.99 0.96 -0.11 -0.03 North Melbourne 2014 0.99 1.03 -0.04 -0.03 Port Adelaide 1999 0.99 0.99 -0.02 0.00 Richmond 1999 0.99 1.01 -0.12 0.00 St Kilda 2011 0.99 0.94 -0.14 -0.07 St Kilda 2016 0.99 0.97 0.03 0.02 Western Bulldogs 2013 0.99 1.09 0.06 0.06 Adelaide 1999 0.98 0.93 -0.18 0.00 Collingwood 1998 0.98 0.00 0.00 0.00 Collingwood 2014 0.98 0.98 -0.19 -0.06 Geelong 2006 0.98 1.03 -0.16 -0.01 Hawthorn 2002 0.98 0.94 0.13 -0.01 West Coast 2002 0.98 0.98 0.22 0.05 Brisbane 1998 0.97 0.00 0.00 0.00 Carlton 2016 0.97 0.98 0.18 -0.02 Essendon 2009 0.97 0.97 0.11 0.03 Fremantle 1998 0.97 0.00 0.00 0.00 North Melbourne 2002 0.97 0.99 0.03 0.02 North Melbourne 2004 0.97 0.99 0.03 0.00 North Melbourne 2008 0.97 0.99 -0.03 -0.06 North Melbourne 2015 0.97 1.02 -0.02 0.00 Port Adelaide 2000 0.97 1.01 -0.02 0.03 Richmond 2001 0.97 1.06 0.03 0.03 Richmond 2008 0.97 1.06 0.09 0.10 Western Bulldogs 2014 0.97 1.02 -0.02 -0.07 Essendon 2004 0.96 0.98 -0.06 -0.04 Fremantle 2003 0.96 0.98 0.04 0.05 Fremantle 2004 0.96 0.98 0.00 0.00 Fremantle 2010 0.96 0.98 0.09 0.03 Geelong 1999 0.96 0.98 -0.03 0.00 GWS Giants 2015 0.96 0.95 0.12 0.03 North Melbourne 2005 0.96 0.99 0.00 0.00 Melbourne 2006 0.96 0.97 0.01 0.02 Port Adelaide 2005 0.96 0.98 -0.06 -0.05 St Kilda 2015 0.96 0.94 0.15 -0.02 West Coast 2009 0.96 1.06 0.11 0.04 Adelaide 2011 0.95 0.97 -0.17 -0.01 Collingwood 2004 0.95 0.96 -0.10 -0.12 Fremantle 1999 0.95 0.97 -0.02 0.00 Melbourne 2003 0.95 0.96 -0.06 0.00 Melbourne 2005 0.95 0.95 -0.16 -0.04 Port Adelaide 2008 0.95 0.95 -0.10 -0.10 Richmond 2000 0.95 1.04 -0.05 0.03 Richmond 2003 0.95 1.04 0.03 -0.02 Western Bulldogs 2000 0.95 1.05 -0.11 -0.03 Western Bulldogs 2001 0.95 1.06 0.00 0.01 Brisbane 2005 0.94 0.94 -0.27 -0.16 Brisbane 2006 0.94 0.96 0.00 0.02 Brisbane 2013 0.94 0.95 0.07 -0.01 Essendon 2006 0.94 0.98 0.04 0.01 North Melbourne 1999 0.94 1.03 -0.06 0.00 North Melbourne 2001 0.94 0.97 -0.06 -0.05 North Melbourne 2003 0.94 1.00 -0.03 0.00 North Melbourne 2006 0.94 0.99 -0.02 0.00 North Melbourne 2010 0.94 0.97 0.10 -0.02 Melbourne 1999 0.94 0.96 -0.13 0.00 Port Adelaide 2010 0.94 1.01 0.02 0.02 Richmond 2006 0.94 1.02 -0.07 -0.09 St Kilda 2001 0.94 0.92 0.06 -0.07 Sydney 2000 0.94 0.93 -0.10 -0.11 Western Bulldogs 2002 0.94 1.07 -0.01 0.01 Collingwood 2000 0.93 0.98 0.02 -0.04 Hawthorn 2006 0.93 0.96 0.05 0.04 Melbourne 2001 0.93 0.95 -0.18 -0.04 Sydney 2009 0.93 1.01 -0.10 0.00 Western Bulldogs 2004 0.93 1.00 0.04 0.06 Western Bulldogs 2012 0.93 1.03 0.03 0.03 West Coast 1998 0.93 0.00 0.00 0.00 Fremantle 2002 0.92 0.93 0.02 -0.03 Fremantle 2005 0.92 0.97 -0.03 -0.01 Hawthorn 1999 0.92 0.97 0.03 0.00 Port Adelaide 2006 0.92 0.99 -0.04 0.01 Port Adelaide 2009 0.92 0.99 -0.03 0.04 Richmond 2002 0.92 1.06 -0.05 0.00 West Coast 2013 0.92 0.98 -0.22 -0.04 Brisbane 2010 0.91 0.92 -0.08 -0.05 Carlton 2007 0.91 0.96 0.07 -0.01 Collingwood 1999 0.91 1.02 -0.07 0.00 Fremantle 2000 0.91 0.95 -0.04 -0.02 Fremantle 2011 0.91 0.99 -0.05 0.01 Gold Coast 2013 0.91 0.99 0.18 0.10 Richmond 2011 0.91 0.94 0.01 0.00 Carlton 2002 0.90 0.94 -0.28 -0.15 Carlton 2005 0.90 0.96 0.04 -0.05 Essendon 1998 0.90 0.00 0.00 0.00 Fremantle 2001 0.90 0.96 -0.01 0.01 Gold Coast 2014 0.90 0.97 -0.01 -0.02 Richmond 2010 0.90 0.94 0.06 -0.08 St Kilda 1998 0.90 0.00 0.00 0.00 St Kilda 2013 0.90 0.98 -0.21 -0.02 West Coast 2000 0.90 0.93 -0.10 -0.02 West Coast 2010 0.90 0.97 -0.06 -0.08 Carlton 2014 0.89 1.01 -0.15 -0.05 Essendon 2005 0.89 0.98 -0.07 0.00 Essendon 2015 0.89 0.95 -0.25 -0.07 Hawthorn 1998 0.89 0.00 0.00 0.00 Melbourne 2011 0.89 0.96 0.02 -0.03 St Kilda 2000 0.89 1.00 -0.16 0.01 St Kilda 2002 0.89 0.95 -0.05 0.02 Western Bulldogs 2011 0.89 1.00 -0.16 -0.06 Essendon 2007 0.88 0.98 -0.06 0.00 Essendon 2010 0.88 0.99 -0.10 0.02 Hawthorn 2005 0.88 0.93 0.06 0.01 Richmond 2007 0.88 0.97 -0.06 -0.05 Western Bulldogs 2003 0.88 0.94 -0.06 -0.13 Western Bulldogs 2007 0.88 0.89 -0.13 0.00 Collingwood 2005 0.87 0.97 -0.08 0.01 Fremantle 2009 0.87 0.95 -0.16 -0.06 Melbourne 2010 0.87 0.99 0.04 0.09 Brisbane 2012 0.86 0.96 0.05 0.05 Carlton 2004 0.86 1.01 0.03 0.02 Essendon 2008 0.86 0.95 -0.02 -0.04 Melbourne 2007 0.86 0.95 -0.10 -0.02 Port Adelaide 2012 0.86 0.97 0.13 0.04 Fremantle 2016 0.85 0.95 -0.31 -0.12 Hawthorn 2000 0.85 0.97 -0.08 -0.01 Hawthorn 2001 0.85 0.94 0.01 -0.02 Richmond 2004 0.85 1.00 -0.10 -0.04 West Coast 2008 0.85 1.01 -0.22 -0.10 Brisbane 2014 0.84 0.89 -0.09 -0.06 Carlton 2003 0.84 0.99 -0.06 0.05 Carlton 2006 0.84 0.97 -0.06 0.01 Gold Coast 2016 0.84 0.95 0.05 0.03 GWS Giants 2014 0.84 0.92 0.17 0.05 North Melbourne 2009 0.84 0.99 -0.13 0.00 Melbourne 2009 0.83 0.90 0.08 0.00 Melbourne 2015 0.83 0.99 0.06 0.00 Richmond 2009 0.83 1.02 -0.14 -0.05 Brisbane 2015 0.82 0.93 -0.02 0.04 Hawthorn 2004 0.82 0.91 -0.21 -0.01 Richmond 2016 0.82 1.00 -0.26 -0.06 Brisbane 2011 0.81 0.91 -0.10 -0.02 Melbourne 2012 0.81 0.92 -0.08 -0.04 St Kilda 2014 0.81 0.96 -0.09 -0.03 Essendon 2016 0.80 0.92 -0.09 -0.03 Carlton 2015 0.79 1.00 -0.10 -0.01 Gold Coast 2015 0.79 0.92 -0.11 -0.05 Gold Coast 2011 0.78 0.95 0.00 0.00 Melbourne 2014 0.78 0.99 0.09 0.15 West Coast 2001 0.76 0.93 -0.14 0.00 Melbourne 2008 0.75 0.90 -0.11 -0.04 Brisbane 2016 0.74 0.90 -0.08 -0.02 Gold Coast 2012 0.73 0.90 -0.06 -0.05 Port Adelaide 2011 0.73 0.93 -0.21 -0.08 Melbourne 2013 0.69 0.84 -0.11 -0.08 GWS Giants 2013 0.67 0.88 0.05 -0.03 GWS Giants 2012 0.61 0.91 0.00 0.00 Team Season