This graph shows Newcastle's cumulative points total along with certain points per game targets (relegation, top 4 and title winners). It is not pretty.
Newcastle were rolling along at a good pace until game 17 and then that good form stopped. A blip became a slump; a slump turned into questions about the managers competence. Such is life, I guess. But why have Newcastle slumped so badly?
Newcastle's recent schedule isn't overly difficult and injuries (bar Remy) aren't a major factor either. Has there been some fundamental change in the way Newcastle play; are they taking fewer shots or shots on target and does this explain the recent inability to record points?
Newcastle's Share Of The Shots (Rolling)
Shots and shots on target are a pretty good, if not entirely complete, tell on team's ability to dominate games. Take more shots than your opponents over a large enough sample and you are likely to be a fairly good team.
Newcastle's share of the shots (TSR) is 7th best in the Premier League.
Newcastle's share of the shots on target (SoTR) is 8th best in the Premier league.
That sounds about right and those numbers are pretty good. As you can see from the trend line above, Newcastle's shots numbers have been consistent and consistently good for the majority of the season. But those trend graphs don't explain Newcastle's slump in form.
So what does explain Newcastle's slump?
PDO is a meaningless acronym created by a normal hockey dude in a moment of genius-like creative thinking. PDO is the sum of a teams scoring% (goals for/shots on target for) and Save% (goals against/shots on target against).
Scoring% average is 30%. Save% average is 70%. Add those two numbers together and we create a stat called PDO,whose average is 100. PDO is commonly, if not entirely accurately, referred to as "luck". It is a stat which regresses toward the mean, which is volatile over a small number of games and, depending if a team has a high or low PDO, can distort how well we think our team is playing.
See that straight black line up there on that chart? That is average PDO and we can see that Newcastle have rarely been an above average PDO side. Newcastle could be shooting from poor areas of the pitch and allowing the opposition to shoot from good areas of the pitch and you Newcastle fans will be able to tell me if that is true or not. But, good shots locations or not, there is definitely some good and bad fortune involved in the rate at which Newcastle convert their chances and the opposition convert theirs (PDO).
So what effect does Newcastle's poor PDO have on the teams ability to score goals and get points? See that green line in the graph above that has been trending downwards for the past 11 or 12 games? That is Newcastle's Goal%, basically it's goal difference presented in percentage form. Newcastle's Goal% has been sliding for a third of the season and the reason for that slide can be found in the black trend line immediately above it - PDO.
Back to the initial question: Why Have Newcastle Slumped So badly?
Well it's not due to schedule quirks and Newcastle's recent injury data, although getting worse, doesn't appear to be the cause. Newcastle's shots data is not the cause either - it is actually pretty good! Newcastle's recent slump is caused byPDO which has dragged the Goal% down and affected Newcastle's ability to record points.
Newcastle's poor PDO may not be all luck: it may be made up of poor shots locations, poor goaltending, wasteful strikers, bad tactics, score effects and some bad luck. But whatever it is made up of it is the easy and available stat that we can point to that is the main cause of Newcastle's poor form.
The thing about PDO is it tends to be volatile and changeable. Newcastle's PDO is low right now but it is unlikely to stay that way for a sustained period unless there are fundamental flaws with Newcastle's tactical system. Newcastle, despite that poor PDO, are excelling at one really important thing: the ability to outshoot the opposition in both shots and shots on target, which can cover for some of the poor PDO that the club is suffering through right now.