They didn't play in anything like as high a line. We played counter-attacking football at Maguire's best; soaking up pressure deep and hitting on the break. This is optimal for slower defenders.
ten Hag has his men way up the pitch playing aggressive, football. One break of those lines and recovery pace is absolutely vital. So either you don't make those mistakes, or athleticism bails out the backline. Two proactive defenders aren't even positioning themselves to run backwards let alone being too slow to get at a forward if they were already in the optimal position to do so initially.
I doubt the manager will make concessions with what he wants in a backline because it sets the tone for the entire team. I don't know how we'll set up exactly, but I'd bet the backline will be high, proactive and look very inviting to play in behind.