Friday, 4 August 2017

What Might Leicester Get from Kelechi Iheanacho?

Hidden behind Neymar's unveiling in Paris was Kelechi Iheanacho's departure from Manchester City to last season's Champions League quarter finalists, Leicester City.

There's probably no need to measure the height of Iheanacho's transfer fee in piles of tenners, but it does amount to a substantial investment in young talent for the East Midlands side and an opportunity  for Kelechi to gain larger amounts of playing time, especially from kick off.

His stats are impressive for a young player.

Any playing time at such a raw age, particularly at a regular title contender is impressive and during his 1275 minutes he's scored 12 from 50 shots (24% conversion rate, without the need for a calculator) and provided 4 assists.

Many appearances have been from the subs bench and it is well known that scoring generally accelerates as the game progresses, so he'll have had a slight boost from that.

He's not really been thrown in solely against the Premier League minnows.

The weighted expected goals conceded by the teams he has faced is only slightly above the league average and he's scored against teams such as Stoke, Spurs, Stoke, Manchester United, Bournemouth, Stoke, Swansea and Southampton.

Nothing too much to worry about him being a flat track bully, although he does quite like Stoke.

In simpler, pre expected goals times, you would take his 24% conversion rate and regresses it fairly heavily towards the league average rate to get a more realistic future expectation.

Devoid of any shot location context, Iheanacho's conversion rate since 2015/16 is second only to Llorente at Swansea, another 50 odd attempt player and just ahead of renowned goalscorer, Gary Cahill.

Small samples often lead to unrepresentative extremes and if any media outlet is still quoting raw conversion rates in this enlightened era, they'll probably be disappointed in the long run.

Higher volume shooters over the two seasons Iheanacho's been around in the Premier League are peaking at around 18% conversion rates and as a group, players with 40 or more attempts are converting around 1 in ten.

Regressing his 24% rate by around 50% wouldn't have been out of order and back in the day you would probably pitch him it at around a 17% conversion rate, which is still elite and wait for more data.

Nowadays, lots of Heisenberg expG models are attempting to extract the truth from lots of noisy data produced by players whose fitness peaks and troughs, along with their team mates and opponents.

Most will put Iheanacho's cumulative expected goals from his 50 attempts at around 9 expG compared to his actual total of 12 goals.

Act is > ExpG, case solved, he's an above average finishing capture.

But this doesn't account for natural randomness in a process or outrageous good fortune (such as
the ball hitting you on the back and looping into the net against Swansea in December 2015).

Here's the range of simulated successful outcomes for an average finisher, assuming he could have got onto the end of Iheanacho's 50 attempts.

There's roughly a 14% chance an average Premier League finisher scores as many or more goals than the 12 that Leicester's new signing managed at Manchester City and his highlighted 24% strike rate slightly pales under the scrutiny of shot type and location.

It's also wise to see if your Heisenberg model at least roughly matches the actual distribution of output from the many guinea pigs who are run through it.... and Inheancho is initially a pretty poor fit.

The chance that his actual distribution of goals from his attempts is consistent with the model used in the simulations, is only around 1 in 1000.

In these cases it is well worth looking at each attempt, the outcome and the attached expG value.

The problem with Iheanacho fitting the model is that two of his goals come from very low probability chances (the aforementioned back deflected goal at Swansea) and the remaining ten come from virtually the ten most likely goal scoring opportunities he received.

He's scored one long range shot against Southampton, one with his back against the Swans and then nails almost every high quality chance with an expG above 0.4 that he's presented with.

Mitigate for the fluke and the model fit becomes more forgiving.

Delving into the attempts, looking at the outcomes and seeing where the (imperfect) model breaks down can tell us a lot more about Leicester's £25 million purchase than merely saying "he over-performs his ExpG".

He may thrive on quality chances, he certainly has done in his short time in the Premier League.

Over the previous two campaigns, Manchester City created the second highest proportion of the high quality chances that Iheanacho excels at converting.

Around 7% of Manchester City's created attempts have an ExpG in excess of 0.4 in my model.

Leicester are third in this list over the last two seasons, also with around 7% of their chances being high quality ones, suggesting he's a decent fit for the Foxes.

However, numerically, Manchester City are much more prolific both overall and in this creative area. Their play makers carve out five such highest quality chances every four games, compared to just three for Leicester.

Iheanacho may be able to bridge that gap between the two Cities by his positional nous and undoubted pace, but he'll also be competing with Leicester's main beneficiary of these high quality chances, a quarter of which fell to Jamie Vardy.

In short, just a few caveats to one of the upcoming season's major purchase by a team outside the top six.

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