Mavropanos clears Calafiori header off the line

2 articles · Updated · The Guardian · May 10

Rice's inswinging free-kick was glanced on at the near post, beat Hermansen and looked set to score before the intervention.
Mavropanos, facing his own goal, hooked the ball away superbly and triggered a frantic scramble in front of goal.
West Ham eventually cleared their lines after sustained pressure, denying the attacking side from a dangerous set-piece.

How did one goal-line clearance by a former player potentially decide both the Premier League title race and a relegation battle?

What is the multi-million-pound value of Konstantinos Mavropanos's single defensive action for both West Ham and Arsenal's futures?

Arsenal leads the league with 21 set-piece goals. Why did their greatest strength fail them at the most critical moment?