Ranking each Premier League team's most important player during build-up play in 2019-20 using data analytics: Part 2

A follow-up to Part 1, Part 2 takes into account the next 5 PL teams, based on alphabetical order, and the figures that are central to their build-up play.

Ask anyone the name of the first human to ever walk on the moon. There’s a high chance they’ll know the answer to that. Ask them who the second human was. The answer to this question? Not so much. This analogy holds water even when it comes to team sports.

In football, for example, attackers that finish the move are the ones that are glorified, more often than not. Not the one that made the defence-splitting pass, not even the guy with the assist, but the guy who tapped the ball into an empty net. Come to think of it, the players that make the final pass before the goal is scored are recognised too, to an extent. But what about those players who were vital in the build-up to the goal?

Often overlooked, these players don’t receive the same accolades their attacking counterparts receive, but there’s probably a good reason for it. How do you quantify their contributions to a goal? It’s not as black or white as a goal or no goal, or, assist or no assist.

Sure, as humans, by virtue of the complex brain we possess, we can attribute some value to it. But you can’t possibly quantify their contribution consistently, repeatedly, and in an unbiased fashion for every pass completed in every game played.

This is where xGBuildup comes in handy. Although it has its own inherent flaws, it does a good job in identifying and highlighting the players that are important to a team’s build-up play. xGBuildup came into existence due to xG or expected goals.

xG is so important today that it has become part and parcel of the way players and clubs alike, are incentivised. As mentioned in the video below (view from 15:15 to 16:29), players and coaches are now getting incentivised on their expected goal tally, instead of their actual goal tally, by a few forward-thinking clubs.

This way “Clubs are rewarding the process, rather than the outcome” according to Omar Chaudhuri, the Head of Football Intelligence at 21st Club.

So now (hopefully!), you understand what xG is and why it’s important, but what about xGBuildup. How is that calculated, you ask? It’s actually really intuitive.

Let me explain using an example. Let’s take the goal Christian Eriksen scored against Manchester United on 31st Jan 2018 (Video for the goal starts at 0:48 in the tweet below). It was the 3rd fastest goal in PL history (the ball hit the back of the net 10.54 seconds after kickoff).

This is how the ball progressed. Mousa Dembélé kicked off the proceedings and passed the ball back to Vertonghen who optimistically lobbed the ball towards the United penalty box. Harry Kane headed the ball into Dele Alli’s path who backheeled it towards an onrushing Eriksen, who slotted home the ball from just outside the 6-yard box.

In other words, the ball progressed like this –

Dembele => Vertonghen => Kane =>Alli (assist) => Eriksen (goal).

Let’s assume that the expected probability of the goal being scored under those particular circumstances (i.e. from that distance, angle etc) by Eriksen is 0.4 or in other words, the xG of that goal is 0.4.

Formerly, only Eriksen would have been rewarded with an xG of 0.4. But now, xGBuildup can reward the players who were involved in the build-up to this goal (or for that matter even in the build-up for any passage of play that just ended up in a shot)

In this passage of play, every player involved other than the player who provides the assist and the player who scored, is rewarded. That is, in this case, Dembele, Vertonghen and Kane are all rewarded with a 0.4 addition in their xGBuildup tally. According to StatsBomb, xGBuildup can be calculated in the following manner:

1. Find all the possessions each player is involved in.

2. Find all the shots within those possessions.

3. Sum the xG of the shots

4. Assign that sum to each player, however, involved they were.

As illustrated in the example of Eriksen’s goal above, xGBuildup is found for every shot taken by a team. Therefore, if 6 players are involved in a passage of play that ends up in a shot, the 4 players that are involved in the build-up before the assist and the goal, will get rewarded with the xG of that shot.

Hopefully, this example helps in understanding xGBuildup and its value as a statistical metric. (This statistical metric can be used by teams to smother their opponent’s attacks by marking their most important player, during their build-up play, out of the game. This can have a lasting effect on the game, as Jorginho himself has admitted more than once)

But using the raw xGBuildup metric without normalising it over 90 minutes does not make any sense. This is because xGBuildup value for a player who has been on the pitch for a longer time will tend to be greater. So, to level the playing field, we can divide a player’s “xGBuildup” value by his “Total Minutes Played” value to get xGBuildup/Total Mins. After this is done, we can multiply this value by 90 to get xGBuildup/90 or xGBuildup Per 90 minutes

xGBuildup/90 = (xGBuildup/Total Minutes Played) * 90

18 out of the 20 clubs before the start of this game-week had played 21 games in the EPL. That’s a maximum total of 1890 minutes (21*90, excluding extra time). To make sure we don’t encounter any outliers or players who weren’t regularly involved, any player who appeared for his club for less than 800 minutes (out of a possible 1890) was excluded from this list. This means that all the players in this list have at least 800 minutes under their belt this season

So here it is (the teams appear in alphabetical order). Listing every Premier League team’s most important player during their build-up of play in this season

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#6 Chelsea – Jorginho: xGBuildup Per 90: 0.584

Newcastle United v Chelsea FC - Premier League

Jorginho was widely reported to have sealed a deal to Manchester City as close as a week before he signed for Chelsea in 2018. Ergo, it would only make sense that he ranks high on this list. Jorginho has the largest value for xGBuildup Per 90 in the league if we don’t consider Man City players (As it happens, Jorginho is 7th in the list, but the first 6 are all Manchester City players). He had the largest xGBuildup Per 90 for Chelsea last season as well, but the circumstances weren’t all the same.

A lot has changed since last season. From being booed during Sarri’s tenure and breaking a PL record for the most number of passes while still not being able to conjure a goal in a pedestrian performance against West Ham, to getting liberated under Lampard, he’s been through a lot.

This season, he has the lowest Unsuccessful touches per 90 in the premier league, by any midfielder with over 10 appearances (0.4 Per 90). He had 0.9 per 90 last season. Additionally, he ranks highly on the interceptions table as well. He has the 5th highest Interceptions per 90 by any midfielder with more than 10 appearances (2.1 per 90).

In addition to remaining vital during the build-up of play, Jorginho has also started owning the game from the midfield, something his manager had said about him as far back as game-week 3.

#7 Crystal Palace – James Tomkins: xGBuildup Per 90: 0.179

Huddersfield Town v Crystal Palace - Premier League

This one is a surprise entry. One of only 2 central defenders to make this list, Tomkins has been a revelation of sorts. He has not only been actively involved in Crystal Palace’s (rare) build-up play but also been tackling with astounding accuracy.

The Premier League veteran has attempted 28 tackles in total but this figure isn’t surprising in itself. It’s actually pretty low, about 2 tackles per 90. The league’s top tackler, Ricardo Pereira averages just above 4 per 90. What’s astonishing is how accurate he’s been at it.

He has been dribbled past only 3 times, successfully tackling 25 times out of a possible 28. That’s an 89% success rate (Virgil van Dijk has a 79% success rate => 15/19), only eclipsed by Seamus Coleman in the PL (considering only defenders with more than 9 league appearances).

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#8 Everton – Gylfi Sigurdsson: xGBuildup Per 90: 0.211

Everton v Crystal Palace - Premier League

It won’t be harsh to say that Gylfi Sigurdsson hasn’t really hit the same heights in the blue of Everton that many expected him to hit, based on his form at Swansea. Only 4 players in the Premier League had more assists than he had during the 3 seasons he was at Swansea. Also, only 16 other players, most of them strikers, scored more non-penalty goals than he had.

He was so prolific during his time at mid-table Swansea that he was one of only 3 players to have scored 20 or more goals and assisted 20 or more goals in those 3 seasons (14/15, 15/16, and 16/17). The other two players were part of table-toppers Arsenal and Spurs (Sanchez and Eriksen).

Although at a bigger club now (albeit an unstable one), Sigurdsson ranks 41 on the top assist makers table and 37 on the top non-penalty goals scorer’s table. A major reason for that is probably his lack of game time. During his 3 year stint at Swansea, he played 87.4% of the Swansea’s minutes in the PL. For Everton, just 79.1%.

Additionally, out of the 21 games that he has been a part of this season (including substitute appearances), he’s played as an attacking midfielder only 12 times. This would explain Sigurdsson’s increase in xGBuildup Per 90 from 0.147 (last season) to 0.211 (this season).

Last season he was 12th on Everton’s list of highest xGBuildup Per 90. A drop in his goals and assists numbers but an increase in his involvement during Everton’s buildup can be attributed to the fact that he is being used as a facilitator rather than an executioner this season

#9 Leicester City – Ben Chilwell: xGBuildup Per 90: 0.341

Leicester City v AFC Bournemouth - Premier League

Leicester City haven’t paid a dime in transfer fees to secure a left-back since the season they got promoted to the PL. If signing Christian Fuchs on a free wouldn’t have turned out to be the coup it was billed to be, they could turn to the budding left-back waiting in the wings.

Fresh from winning the Academy Player of the Year award at the end of the 2014-15 season, Ben Chilwell was made a part of the first team roster in Leicester’s title-winning season and has never looked back since. He has become a vital part of Leicester’s back 4 since the time he was asked to deputize for the veteran Austrian full-back.

Only 3 other Leicester City players have more assists than Chilwell’s 9 since the start of the 2017/18 season. Only 5 other PL defenders have more assists than he has in that period.

Unsurprisingly, Chilwell has been strongly linked to many of the traditional Big 6 clubs. Being touted to take over from César Azpilicueta won’t be easy at all, but one thing he can match the Spanish full-back for is his perennial presence in the playing 11.

Chilwell started 36 out of the 38 games last season, playing 3240 minutes. Only 13 other outfield (Azpilicueta was, of course, one of them) players played more minutes than him. An interesting thing that stood out is that Chilwell is the youngest player in the Top 25 outfield players who played the most minutes last season (he’s only 23 years old!).

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#10 Liverpool – Andrew Robertson: xGBuildup Per 90: 0.478

Andrew Robertson and Van Dijk celebrate a goal.

Do you want to hear something that will blow your mind? 2888 players have played in the top 5 leagues since the start of the 2018/19 season. That’s not the shocking part. What’s shocking is that only 6 out of the 2888 players have more assists than Robertson during that time.

Only 1 other defender, in the top 5 leagues, has more assists than him during that period. It is 21-year-old Trent Alexander-Arnold (who has more assists than Messi over those games, just by the way). The PL defender that comes in third, in this list, is Ricardo Periera with 7 assists, a return that is respectable but pales in comparison to that of the Liverpool defenders.

If you think this is just good form, check this out. Only 5 other PL players have provided more passes into the penalty area than Robertson has (excluding set pieces). That’s more than the likes of Mane, Sterling, Aubameyang, and Alex Iwobi. Oh, and in case you forgot, each of them was bought for at least 4 times what he was bought for (only 4 defenders occupy spots in the Top 30 for passes into the penalty area, Robertson is one of them).

This is the end of Part 2 of this 4 part series. To reiterate why recognising the unsung heroes of teams is long overdue, here is what Buzz Aldrin, the second man to step on the moon had said when he was asked how it felt to be called the second man on the moon.

“But after years and years of being asked to speak to a group of people and then be introduced as the second man on the moon, it does get a little frustrating. Is it really necessary to point out to the crowd that somebody else was first when we all went through the same training, we all landed at the same time and all contributed? But for the rest of my life I'll always be identified as the second man to walk on the moon.”

Stat source(s): www.understat.com, https://fbref.com/en/

ICYMI: Ranking each Premier League team's most important player during build-up play in 2019-20 using data analytics: Part 1