WHAT IS HEAT CHECK?
Some teams or players confound quality, form or logic when performing to a high standard - but it's statistically likely that they will return to their expected position before time. A heat check refers to a player or team that might suffer a regression to the mean before long.
It does not mean that they are not good, or haven't been good! It simply means that numbers always win - but it depends on the time period to gauge the relative success of the player or team.
Leicester City
Leicester have had a fantastic season so far, taking advantage of a weak Arsenal and Manchester United to establish themselves as among the the top four contenders - if not more - in the league.
They have quality in every area, from the ever-dependable Jonny Evans, the full-backs in Ricardo Pereira and Ben Chilwell, to the exciting midfield of James Maddison and Youri Tielemans. And with Jamie Vardy still scoring at a prodigious rate, they look a formidable force who can be in the mix for a Champions League position.
And given the form of their rivals, it's likely they will finish there. Leicester are a very good team. But they have been somewhat fortunate on occasion when fate has dealt them a decent hand. Their xG in their 12 games played (according to Understat's model) is 15.7, yet they have scored 28 times. Granted, some of that number is wrapped up in their improbable 9-0 win over 10-man Southampton, and (once again) in their 5-0 mauling of weak (and man-down) Newcastle. But things have went their way in tighter games, too.
In the first two games of the season they were inferior statistically in xG (What is this?) to both Wolves (0.54 v 0.81) and Chelsea (1.23 v 0.95) and were somewhat fortunate to get draws on either occasion based on clear chances created. Furthermore they were outscored on the xG scale by Tottenham in September, only to see a razor-thin offside call fall in their favour before they went on to win the match.
Expected Goals is far from perfect in this regard - the heavy victories they achieved and their ruthlessness against teams with a man less skew the totals slightly - but when looking at the form of both Vardy in front of goal, well, it's good. Too good, you might say.
In the end, the point of Expected Goals is that everything should average out eventually. It's a metric that keeps even the greatest players in check. So when Jamie Vardy is scoring 11 goals against an xG of 5.2, you start to wonder. Even in the season when Leicester tore up every prediction and won the league in 2015/16, Vardy only overachieved his xG by a mere 1.8 (22.2 on his 24 goals). This means that for all the shots and chances he had, he would have scored maybe a goal less.
But his discrepancy at the moment is huge, and he is so clearly the main goalscorer that any of this team-mates are put into the shade. The next Premier League scorer is James Maddison on four, quite a way back, but even for him and everyone else who scored goals - they are all above their xG values.
And it's not just in attack. As of November 16, No-one has conceded less goals than Leicester in the Premier League season (8). Their defence has been bolstered by the promotion of Caglar Soyuncu following the departure of Harry Maguire to Manchester United, alongside an evergreen Jonny Evans who remains a superb defender. They are well-drilled, performing as a unit and are clearly understanding Brendan Rodgers' ideas. But their Expected Goals Against is roughly 13, meaning they should have conceded five more goals than they have.
In short, this is a good team, filled with good players, playing good football. But sometimes it's too good to be true. Their next three matches are against Brighton (A), Everton (H), and Watford (H), teams who would all want that fixture to be reversed to the opposite venue based on their current form. We'll find out a little more about the Foxes once those games are complete.
