“WHAT an absolute dire match. We wouldn't have scored if we were still playing now,” said one irate Newport County AFC supporter following Saturday’s 1-0 home defeat to Cambridge United.

And that was one of the kinder comments left on the Argus website after the match.

“To call this a dire performance is being kind,” said another. “It was the most abysmal load of rubbish I have seen in years.”

“Two shots on target all game, what's going on?” added a third. “Even the bottom club had over double that today.”

In my match report for yesterday’s print edition, I described the match as “a low-quality game with both sides struggling to create clear-cut chances on a difficult playing surface.”

And even manager Michael Flynn described himself as “shell-shocked” by a performance that was “nowhere near what we expect, what we worked on, and nowhere near the levels that the players have been at lately.”

The Exiles enjoyed 59 per cent of the possession and produced 19 shots to Cambridge’s 10.

But it still came as something of a surprise to see the ‘expected goals’ statistics from the match.

Flynn’s men had an xG score of 2.1 to Cambridge’s 0.9 according to Ben Mayhew, head of data analysis at the Press Association.

That essentially means that the 3,336 fans at Rodney Parade on Saturday should have seen a 2-0 home win rather than a 1-0 victory for the visitors.

And, according to d3d4football.com, County had the highest xG rating in League Two on Saturday with 2.4.

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So what is xG? How is it calculated? And does it mean we shouldn’t believe what we see, or think we see, with our own eyes?

Expected goals (xG) is a predictive model used to assess every goal-scoring chance, and the likelihood of scoring.

An xG model computes for each chance the probability to score based on what are known as event-based variables.

The higher the xG – with 1 being the maximum, as all probabilities range between 0 and 1 – the higher the probability of scoring.

In practice, that means if a chance has 0.2xG, it should be scored 20 per cent of the time. If it has 0.99xG, it should be converted 99 per cent of the time and so on.

A typical xG model considers the following event-based variables when assessing the quality of a chance: distance to the goal; angle to the goal; did the player strike it with his feet or was it a header?; in what passage of play did it happen?; has the player just beaten an opponent?

As an example, a close-range shot from a central position will have a higher xG value than a header from an acute angle, assuming all other factors remain the same.

The idea behind xG is that it gives an indication of whether results are based on sustainable factors like a steady creation of chances, or whether it is down to aspects such as luck or world-class goalkeeping.

For example, if a player has a higher xG figure than actual goals scored, it will likely be a result of poor finishing or bad luck.

If a player is scoring more than his xG, it could be because of individual brilliance.

Put simply, xG can be thought of as effectively evaluating the quality of 'chances'.

Whereas the 'shots on goal' count does not differentiate between a long-range strike and a missed open goal from two yards out, xG does.

As well as helping us to assess individual players, xG also enables the stat people to evaluate teams – and to predict future performances.

For example, if a team is performing to a certain level at the start of a new season, a look at their expected goals could reveal whether that run is likely to continue.

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County have the second-best defensive record in League Two so far this season with only Cheltenham Town able to better their total of 26 goals conceded.

But only bottom club Stevenage have scored fewer goals, with the Exiles netting just 27 times in 29 league games to date.

Flynn has constantly bemoaned the number of chances that his players have squandered throughout the campaign.

And the xG stats suggest that the manager’s assessment of a lack of cutting edge and ruthlessness up front is correct.

Mayhew’s long-term performance trend model for County suggests that they are underachieving in terms of expected goal difference in recent months.

If they can start converting more chances, there may still be life in this season.

Read more: Newport County boss focused on beating Walsall after defeat to Cambridge United