Why do West Ham keep conceding from corners?

West Ham are struggling in the Premier League, languishing in 19th place as head coach Graham Potter faces mounting criticism and internal club scrutiny.

One part of their game that has been particularly concerning is their defending of corners, having conceded seven goals from these situations in five games.

Set-pieces are becoming increasingly important as club employ dedicated coaches who analyse how best to expose upcoming opponents.

BBC Sport has analysed West Ham's poor performance from corners and the tactics teams are successfully using against them this season.

Let's begin by looking at West Ham's 5-1 loss to Chelsea in August, a game in which Enzo Maresca's side scored three goals from corner situations.

One thing that jumped out immediately was the use of Liam Delap, who stood by West Ham goalkeeper Mads Hermansen. Delap was tasked strictly with marking the keeper and limiting his freedom of movement without committing a foul.

This isn't something new. Going back to last season, the use of a 'blocker' was a common tactic.

As a tactic, it resembles 'screening' in basketball, a move in which a player stands still to block a nearby defender, allowing space for their team-mates to move freely around them.

Defending teams tried to counteract this in the Premier League last season by putting an extra defender next to their keeper as a makeshift bodyguard, aiming to absorb the contact from the 'blocker'.

This wasn't always successful as the 'blocker' would begin to push the defender into the goalkeeper, still hampering the keeper's movement and ultimately making that space more crowded.

The second difference from last season is that referees are seemingly less strict on contact with the keeper. It is unclear why this is, but it means it is a more effective tactic for attacking teams to use.

For Chelsea's first goal against West Ham, Delap backed up towards Hermansen, preventing him from coming out to claim the ball. With 11 players in the six-yard box, there was even less room for the keeper to move.

Marc Cucurella darted to the near post, getting his body in front of his marker. Many of Chelsea's attackers moved towards the goal, which pushed their markers deeper.

Cucurella's flick-on therefore found Joao Pedro in space to score in front of the incredibly deep West Ham defence.

In recent seasons, crosses to the near post were favoured by attacking teams. Chelsea opted for this same approach against West Ham too.

Teams often commit extra players to the near post as a way to prevent dangerous flick-ons in this area, so naturally there are fewer players elsewhere, which includes the far post. As a result, some teams are deliberately choosing to cross to the far post from corners and with good success.

Against Spurs on 13 September, West Ham appeared to place more players towards the near post, perhaps as a result of Chelsea's previous success against them in that area.

Spurs instead targeted the far post where West Ham had fewer players. Spurs put two attackers at the far post to West Ham's one defender, meaning eventual scorer Pape Matar Sarr was left unmarked.

Spurs didn't block the goalkeeper like Delap did for Chelsea, but they did use blocking in another interesting way.

With a looping ball played to the far post, Potter's West Ham players tried to move from the near post towards the ball. As the Spurs' attackers were positioned behind them, they were able to hold their ground, blocking the West Ham players' path. This prevented any West Ham defender from getting close to Sarr.

With the number of players in the six-yard box, Hermansen was again unable to leave his line too.

Sarr headed the ball in before running off in celebration, pointing to set-piece coach Andreas Georgson.

This final example is perhaps the best.

In West Ham's loss to Crystal Palace this past weekend, Oliver Glasner's side scored from a corner and pulled together all of the tactics mentioned here into one set-piece routine.

Jean-Philippe Mateta copied Delap's role and 'stood on' goalkeeper Alphonse Areola, acting as a blocker. This prevented Areola from leaving his line.

At the far post, Palace used blockers again, this time in a very similar way to the idea of screening in basketball. Adam Wharton put his body between Marc Guehi and his marker, blocking the West Ham defender's path. This meant Palace's captain was able to break free unmarked.

Daichi Kamada's looping cross was aimed towards the far post. Palace's Chris Richards and Maxence Lacroix, standing behind their markers, prevented West Ham's defenders from moving towards the far post, in a similar fashion to Spurs' goal.

Guehi's header cannoned back off the bar and Mateta was best positioned to nod home unmarked because he was standing by the goalkeeper rather than with a defender.

Set-pieces routines are becoming increasingly complex.

Marking the goalkeeper, crowding the six-yard box, overloading the far post, playing looping crosses, blocking defenders' path to the far post, and screening manoeuvres to free a player from their marker - these are all tactics top teams have used to trouble West Ham.

If West Ham are going to turn around their fortunes, under Potter or otherwise, it is key they turn their set-piece frailties into a relative strength as has been so common for West Ham in recent years.