Why Thomas Tuchel is picking John Stones over Marc Guehi for England vs Croatia

England's World Cup hasn't even got underway but already there is one Thomas Tuchel decision which could define the Three Lions tournament: John Stones over Marc Guehi .

Mirror chief football reporter John Cross reported on Tuesday that Thomas Tuchel "loves" Ezri Konsa for his "pace, tenacity and reading of the game" and that his place in the starting lineup is pretty much certain. In his predicted XI, Cross suggests Tuchel's "tighest call" would likely see Three Lions veteran Stones get the nod over his former Manchester City team-mate - despite Guehi being pretty much England's first pick at centre-half for the past three years.

Cross added: "Guehi probably thinks back to Tuchel’s first game in charge of England and he did not start - and still wonders whether the ex-Chelsea boss who let him go from Stamford Bridge really fancies him. But that is probably in Guehi’s mind."

On the surface, it sounds like a strange call - a perennially-injured 32-year-old who has left his club at the end of his contract, preferred to his 25-year-old replacement at club level and a man who has been one of the Premier League's most dependable centre-backs in recent years.

You'd be forgiven for thinking Tuchel was acting on reputation. Stones has always been a tremendous talent and, for many, Guehi included, England's best centre-back of the last 15 years, but there's no doubting Guehi has had the better spell in the lead-up to the tournament.

But looking at both through Machine Football 's model, a different picture emerges, with no sentimentality to be found. Instead, if Stones really does start against Croatia , it will be a tactical decision based on one thing alone: set pieces.

Marc Guehi v John Stones in stats (Opta)

Tuchel has made no secret of the fact he's focused on maximising England's performance at dead-ball situations. If this is to be treated as a priority, one statistic stands out above all others.

Machine Football ranks Stones in the top 1% globally for heading ability. Not just among centre-backs, not just among Premier League defenders - across every single player in the database.

Guehi, meanwhile, is closer to the average. He sits in the 48th percentile for defensive headers among centre-backs - a truly mammoth gap between the two potential starters.

Stones is far from the biggest defender, but despite standing just two inches taller than his rival he is - simply put - one of the best aerial defenders in football.

That's important when you're a high-pressing team that's expected to dominate possession and force your opponents into going long - but it's absolutely essential when considering that Tuchel has made it clear that set pieces will be a major part of England's approach at the tournament.

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The deliveries are accounted for already. Declan Rice averaged 4.51 corners per 90 during England's World Cup qualifying campaign, and ranks in the top 5% globally for crossing according to the model.

It's been reported that Tuchel will be embracing Arsenal's set-piece skill - and if Bukayo Saka starts that's another master of delivery.

Marcus Rashford is also something of a dab hand for deliveries himself and took set pieces regularly for Barcelona last season, averaging 4.31 corners per game in La Liga .

So that leavs the question of who will be on hand to attack those deliveries.

With Harry Maguire left out, alternative aerial threats will need to be identified. Stones arriving at the back post is a very different proposition to Guehi - and Tuchel knows it.

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None of this means Guehi is a bad player. In fact, the model suggests he has probably surpassed Stones in terms of his recovery pace, his all-round game and is now the more complete centre-back.

Guehi ranks in the top 5% globally for creativity and passing accuracy, exceptional numbers for a defender. He also scores higher than Stones for tackling, ball recoveries and defensive actions.

In many ways, Guehi is the successor to Stones in the club game - an innately expansive centre-back capable of influencing the game across the pitch, and his estimated transfer value in the model of £82m (around 10 times Stones' £8.4 m value) reflects this along with his age, availability and long-term potential.

Across an entire league season, it's easy to argue Guehi is the better option. But in a knockout tournament this is by the by. Tuchel's job, at the end of the day, is to pick a team that gives England the best chance of winning one-off games.

The one painfully obvious concern with John Stones is his availability. The former Everton man has had an incredible career, but injuries have hampered his recognition as one of the world's very best.

Across the last season, Stones made just nine league appearances next to Guehi's 35 - a genuine concern in a tournament where England may need to play seven matches in a month and have already lost Tino Livramento to injury and have concerns over Saka.

But Tuchel will know this better than anyone, watching him every day in training. If he's willing to start Stones, it's because England's coaching staff believe he is fit enough to do the job.

There is certainly a strong case that Guehi is the better defender right now. But that is not necessarily the question that Tuchel is trying to answer.

The German's squad selection was controversial, to say the least. Few could ever accuse him of shying away from an unpopular decision, and this is no different.

England have elite set-piece takers in Rice, Rashford, and Bukayo Saka. As the fourth-ranked side in the world , England expect to dominate territory - which means set pieces become inevitable.

Time after time last season we saw sides that are capable of taking advantage of those situations come out on top in games. For that to work, heading ability matters.