Dan Burn, or rather the lack of, isn't the reason why we've been poor the last couple of games. He's not the reason why Dunk has turned into Mings, Bissouma has been poor since AFCON, Trossard's form and influence has dropped off or the team has lost its cohesion.
I think the sale of Dan Burn has indirectly had some effect. Not in the sense that he himself would stop all the seven goals conceded in the last three games, but more in the sense that never being able to play with the same set of central defenders is creating some anxiety in the team, there's no real stability.
Today: Veltman, Dunk, Cucurella
Burnley: Duffy, Veltman
United: Dunk, Webster
Watford: Dunk, Webster, Veltman
Tottenham: Cucurella, Dunk, Webster
Leicester: Burn, Webster
Six straight games with different combinations in central defense. Sure, GP could technically have started with Duffy-Veltman today just like last week but I dont think that felt like a particularly tempting option.