League 2 trends, 28 Dec 2016

I’ve used the Christmas break to get another new type of graphic finished, which is explained in full here and briefly below.

Explanation

Basically these are adapted from a very similar design by the excellent Swedish blogger Zorba138 intended to track both long-term performance and whether this was an underachievement or an overachievement based on the balance of chances created.

There are two lines: one showing the rolling average of a club’s goal difference over the last 10 league games (blue line) and the other the rolling average of their expected goal difference (red line) based on the quality of chances they’ve created and faced.

Comparing these two allows us to see not only how a club’s performances have changed over time, but also whether there were any differences between the balance of chances created (a useful measure of underlying performance) and goals scored.

These are highlighted in blue (where goal difference is higher than chances created, suggesting overachievement) and red (for the reverse, signalling potential underachievement).

Over the long term we’d expect the two lines to converge unless there’s a significant difference in a club’s attacking or defensive skill compared to the average for the division. We can’t tell from the data alone whether skill or luck is the cause, but the longer a difference persists the more I’d suspect the former.

The graphics

Below I’ve created a graphic for each club (in alphabetical order) with some short commentary for each:

trend-2016-12-28-accrington

Accrington are a real puzzle this season: the red line shows that they’ve sustained their impressively dominant performances from last season, but the tanking blue line shows that this isn’t even close to being reflected in their results.
trend-2016-12-28-barnet

Barnet’s peformances got progressively worse as last season wore on but they somehow sustained a respectable sequence of results. They’ve looked better overall this time around and are currently on the up, but it’s too early to tell if they can secure a top half finish.
trend-2016-12-28-blackpool

After a shaky start Blackpool have been sustaining some above average performances, although in recent weeks their results look to have flattered them slightly. However after two previous seasons spent mostly on the back foot, this is surely shaping up to be a more enjoyable campaign regardless.
trend-2016-12-28-cambridge

It’s already been a rollercoaster season for Cambridge fans: a horrible start has given way to an impressive resurgence, although results have outstripped performances so far. Having made steady progress last season many will surely be hoping for more stability in the second half of this one.
trend-2016-12-28-carlisle

I’m getting a little bit worried about Carlisle’s promotion prospects. Results and performances were impressing in tandem at the start of the season, but the latter have dropped away significantly. Therefore unless the Cumbrians have a big skill advantage over some of the teams around them, they could start to lose ground.
trend-2016-12-28-cheltenham

Given their strong showing in winning promotion, the model had high hopes for Cheltenham this season. However they’ve struggled to carry their momentum over and – while still looking better than their current league position – performances look as though they could deteriorate further.
trend-2016-12-28-colchester

That enormous lake of red in the middle is down to an obscenely leaky defence last season that ultimately got Colchester relegated despite some otherwise respectable performances. There have been minor echoes of the same problem this time around but fortunately they appear to have been nipped in the bud for now.

trend-2016-12-28-crawley

Crawley were in decline for much of last season but have looked much healthier lately, although still in a “bottom half of the table” kind of way. However it’s safe to say that Dermot Drummy’s appointment has paid off so far.

trend-2016-12-28-crewe

It wasn’t a surprise to see Crewe relegated last season as they performed consistently poorly even before their late collapse in form. Some decent initial showings this term have unfortunately given way to another dip of late, but they’d be very unlucky to suffer another relegation this time around.
trend-2016-12-28-doncaster

There’s a lot of red here: Doncaster looked unfortunate to go down last season after some horrible results but have started this campaign well. However like Carlisle they’ve gone off the boil a bit lately and aren’t really dominating games, so some improvement is needed to sustain a top three pace.
trend-2016-12-28-exeter

Exeter spent the second half of last season looking increasingly impressive but a horrible – and unlucky-looking – start to this campaign saw that progress reversed. However they’ve looked much brighter lately, with results and performances rising in step.
trend-2016-12-28-grimsby

This looks far more horrible than it is. After two dominant seasons in the National League, barring a late collapse last term that saw them promoted via the play-offs, the Mariners are now up against much tougher opposition. Their lines are both orbiting the zero line, which suggests some solid mid-table performances and is only so low on the chart because so much of their recent history has been spent dominating matches.
trend-2016-12-28-hartlepool

While they looked better than their poor start to this season, Hartlepool’s performances look to be on the wane overall. Their strong – and perhaps slightly fortunate – finish to the previous campaign maybe raised expectations too high, but overall they look to be in a similar state to 12 months ago (based on the position of the red line).
trend-2016-12-28-leyton-o

The huge amount of red last season suggests that results fell a long way short of performances, to the point where I’d suspect something else was going on: perhaps a bad atmosphere after recent chaos, but I’m speculating. Things haven’t looked anywhere near as good on the pitch this time around unfortunately and improvements may be needed to avoid a relegation battle.
trend-2016-12-28-luton

Luton’s surges of good form over the last two seasons have looked somewhat misleading, with results looking unsustainable and eventually falling back into line with their more modest underlying performances. This time around however the two lines are tracking each other more closely and their strong start looks far likelier to persist.
trend-2016-12-28-mansfield

Mansfield’s season began much as the last one did, with an initial upturn in performances that ended up being short-lived. However they’re performing at a respectable mid-table level overall this term – the red line is hovering around the zero axis – with recent defeats looking more unfortunate than deserved.
trend-2016-12-28-morecambe

Morecambe started last season as overachievers before spending the bulk of it struggling to grind out the results their performances merited, and they’ve already completed the same cycle again this term. Their strong start looked unsustainable but as performances have improved their form remains stodgy. However two wins out of their last three gives hope that a corner is being turned.
trend-2016-12-28-newport

Newport looked to be making genuine improvements until the final 11 games of last season, when everything went suddenly south. With no improvement in sight, the change in manager may have been justified judging by the subsequent upturn in performances, which have yet to dip as sharply as more recent results.
trend-2016-12-28-notts-coThere’s nothing particularly mysterious about the Magpies’ recent dire form: performances have nosedived since the early part of the season. While last season ended with something of a whimper, the underlying data itself (the red line) was encouraging, suggesting that better times were around the corner. However after seven consecutive defeats that renaissance has been wiped out.

trend-2016-12-28-plymouth

Plymouth seem to start every season with a big blue overachievement bubble that disappears after Christmas, and it looks like they may have started deflating it earlier than usual this time around. Their performances have grazed their way into negative territory recently after three successive defeats, so a resurgence will be needed to avoid another failed promotion bid.
trend-2016-12-28-portsmouth

Portsmouth’s red season so far backs up what I’ve seen in the scatter graphics: they’ve been incredibly dominant but haven’t always been able to break opponents down. However their goal difference is still impressively positive and they could well benefit if one of the current top three continues to stumble.
trend-2016-12-28-stevenage

Stevenage began last season in decline as belts were tightened, but after Teddy Sheringham’s departure things began to look up, even though results didn’t always accompany the improved performances. However the upward trajectory seems to have stalled and some generally positive recent results could well be masking some problems.
trend-2016-12-28-wycombe

Wycombe’s chart is one of a few that looks like the club-specific colour scheme continues after the title, comprising mostly blue zones of overachievement. It’s tempting to conclude that they’ve been lucky, but there’s enough of it to make me wonder if Gareth Ainsworth possesses some sort of spooky managerial edge. Either way, after a steady decline in performances last season threatened to continue this time around, they’ve rebounded impressively to storm up the table.
trend-2016-12-28-yeovil

Yeovil looked increasingly solid as last season progressed and, after a poor start this time around, look to have picked up where they left off. Both lines are shooting up as the Glovers recover from that dire early run – the first time that their red line has entered positive territory since they rejoined League 2.