Scatter graphics: Championship, 31 Dec 2017
As we’re at the end of the calendar year and a shade over halfway through the season, here’s another update to the scatter graphics, which compare the attacking and defensive performances of every team in a division. Each of the four graphics is explained briefly below and at length here.
First of all, here is how the number of shots taken by each club compares with those they face in return. The average number of shots taken per match is on the horizontal and the average number faced is on the vertical, so bottom right (take plenty, allow few in return) is good while top left (take few, allow plenty) is bad. The stripes are like contours: the greener the stripe, the better the performance (and vice versa for red).
Brentford are creating an insane amount of chances – almost four more per match than anyone else – and their defence isn’t too shabby either. There are five teams lower than them on the chart who have allowed fewer shots at their goal per match, but all have created a far more modest amount in return.
Meanwhile both Burton and Ipswich are spending a lot of time on the back foot, albeit with vastly different results so far. The rest of the graphics below will shed some light on this.
Now let’s look at attacking alone. The horizontal axis stays the same as in the graphic above, but now the vertical shows the average number of shots needed to score each league goal. Therefore bottom right is good (taking lots of shots and needing fewer efforts to convert) and top left is bad:
Wow. Birmingham have some serious problems up front, as 13 goals scored in 25 matches testifies. They’ve needed more than twice as many attempts to find the net as the average team, and over three times as many as the division’s most clinical teams.
The sharpest finishers of all are Ipswich, which goes a long way towards explaining how they can be sitting in the top half of the table despite creating the third fewest chances so far. Tucked in just behind them are runaway leaders Wolves, who are definitely more about quality than quantity.
Apart from the Blues, the likes of Norwich and that relentless Brentford attack have also had some trouble when it comes to putting the ball in the net so far.
Next let’s look at the defensive situation – basically take the above chart and replace the word “taken” for “faced” on both axes. Now top left is good – facing fewer shots and able to soak up more per goal conceded – and bottom right is bad:
While Sheffield United have allowed impressively few attempts at their goal so far this season, only a handful of sides have dealt less capably with those that have got through. Worst of all has been Hull, which has undermined the relatively sharp attack we saw in the last graphic and should be near the top of the priorities list for Nigel Adkins to address.
Derby‘s defence has been the division’s most resilient so far, second only to Wolves‘ overall. The Rams have allowed a virtually identical number of chances to Hull but have conceded half as frequently. Defence also looks to have been the biggest contributor to Mark Warburton’s sacking at Nottingham Forest.
Finally here’s an attempt at correcting the first graphic for the quality of chances created and allowed, using the same “expected goals” values that power my shot timelines (explained here). The reason for doing this is that the results tend to correlate more strongly with performance than when we treat all shots equally:
When we correct for shot quality there is far less space between Brentford and the rest, suggesting that a fair chunk of the chances they create are of relatively low quality. Wolves and Cardiff look the most impressive overall, but the Bees and Bristol City aren’t too far off their pace.
Sheffield United appear to have the best-performing defence in the division – which more than compensates for a relatively average attack – so there’s plenty to suggest that they’ll be able to remain in the play-off race.
It’s also been a solid return to the division for Millwall, who started the season well and look capable of finishing comfortably in mid-table.
Burton look to be in the most trouble so far, with plenty for fans of Birmingham and Bolton to worry about too. If they hadn’t already built up such an impressive points cushion I’d include Ipswich in this list too.