Why Have So Few Managers Been Sacked In The Premier League This Season?

Sheffield United's Paul Heckingbottom has become the first managerial casualty in the 2023/24 Premier League season, following on from the Blades' 5-0 loss to Burnley at Turf Moor. With the first sacking of the season coming an unusually late 14 weeks into the campaign, just why has there been so few dismissals in the English top flight this season?