How has Cristiano Ronaldo improved Juventus’ offense?

When Cristiano Ronaldo was available in the summer, Juventus had to make the deal; he was the only player that could transform the club both on- and off-the-field (the rape allegation will cast doubt over that commercial revenue boom Andrea Agnelli has hoped for). They have dominated the domestic scene for seven years, and the only on-the-field success they wish Ronaldo will bring is the UEFA Champions League (UCL). But do they have a problem that needs Ronaldo to solve?

 

A recurring problem for Juventus in the UCL has been their lack of firepower; among all the teams that qualified for the final stage, Juventus scored the second-fewest number of goals in 2015-16 (1.25 goals per game, 24% lower than average) and were the third-lowest scoring team in 2017-18 (1.4 goals per game, 24% lower than average). In both seasons they went out of the competition before the quarter-final. When their goal-scoring functioned somewhat close to an average level in 2016-17 (1.69 goals per game, 8% fewer than average), they went all the way to the final and were just a step away from the ultimate glory.

 

Juventus’ problem didn’t come from their chance creation; they created 1.93 Expected Goals (xG) per game in 2015-16 (seventh highest) and 1.83 xG per game In 2017-18 (ninth highest). Interestingly, when their offense was the most potent in 2016-17, Juventus only created 1.52 xG per game, the third fewest in the UCL that year. Their chance creation hasn’t been top-notched, but it has mostly been acceptable and allowed them to hang on with the big boys.

 

The one factor that has dictated Juventus’ offensive performance in the UCL is their chance conversion. Since xG is a probability measure of chance conversion, meaning that a chance with 0.5 xG has a 50% chance to become a goal, we can use goal/xG to measure how well a team converts its chances. In both 2015-16 and 2017-18 when Juventus had problems scoring, their goal/xG ratios were below 0.69, second lowest among all qualified teams in both seasons. In 2016-17 when their goal-scoring was acceptable, they converted 1.22 of xG, the second highest among all the teams for that year. Therefore, because Juventus don’t create a ton of chances, their ability to convert those chances dictate how much goals they can score and how deep a UCL run they can make.

 

Juventus’ problem in scoring has been tough to solve because their offense has already functioned at an optimal level in the same period; from 2015-2018, Juventus has generated no fewer than 1.7 xG and 1.9 goals per game and converted at least 1.07 of xG in Serie A. They were almost playing with an opposing style and efficiency in the domestic league and Europe. For instance, in 2017-18 when Juventus’ offense was functioning at their maximal level in the league, they scored more than 2 goals a game, more than any other season Massimiliano Allegri has been at the realm. They converted more than 1.46 of their xG. That number dropped more than 50% to 0.68 in the UCL. Their overall offensive output wasn’t enough in Europe. They created enough chances, but they couldn’t convert sufficiently against other contenders in the UCL.

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Juventus’ offense has transformed this season. They have scored 2 goals per game, eighth highest in the UCL this year, at least 0.3 goals more than any other season. The actual increase in goals is small, but their chance creation has exploded in Europe; Juventus have created 3.12 xG per game, more than any other team in the UCL in the last four years. The current issue is that they only convert 0.64 of the xG, but that massive amount of xG increase compensates for any of inefficiency in the chance conversion.  Not converting enough xG is undoubtedly a waste, but over the long run, the goal/xG for most competent teams is going to regress towards one (a scientific phenomenon for any probability measure if the model is accurate). Some teams may convert their chances better or worse than the others, but the variation at the top level is small. If you want to score, you want to create lots of chances or xG. Juventus has moved in the right direction to solve the offensive struggle they have had over the last few years.

But we need to be careful to interpret Juventus’ performance in Europe this year because the sample size is small. They have only played three UCL games, and Ronaldo has played in a little more than one. To fully grasp how Juventus has changed we need to use the league’s data. This season, Juventus is scoring two goals a game, similar to last season. But like how they do in Europe, their offense has escalated; they have created 2.68 xG per game in Serie A, 1 xG more than last year and amounts to a 58% increase. Their “lack” of scoring is again due to their inefficiency in front of the goal; they have only converted 0.86 of their xG, lowest since Allegri has taken over. Still, that low proficiency in the goal scoring will eventually bounce back at least close to one for a team like Juventus (regression to the mean). Consider this calculation: if their goal conversion regresses to one after the next ten rounds, Juventus will be scoring more than three goals a game in the league.

Allegri deserves a lot of credit in the successful integration of Ronaldo into the team:

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Ronaldo recorded 1.02 xG in La Liga for Real Madrid last season. Since his arrival in Serie A, he has amassed 1.09 xG. His xG tally is equivalent to Juventus’ xG increase in the league this season. Therefore, even after selling Gonzalo Higuain, Allegri has completely installed Ronaldo’s contribution into Juventus without making others give up their shots. The only exception is Paulo Dybala who is now taking more duties in assisting and building up the offense phase. Allegri needs less than three months to integrate Ronaldo into the team successfully.

The early pieces of evidence suggest that the arrival of Ronaldo has transformed Juventus’ offense. Their problem was the chance conversion. Instead of improving their finishing, which is more difficult and unpredictable to achieve, Allegri uses Ronaldo’s ability to create shots to compensate for their lack of scoring. They are creating so many chances that they can afford to waste a lot of them.

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