Maybe he is under instruction
Unless he's made out of biscuit, then I can't see the instructions being "Whatever you do Sam, don't dive for the ball". As skyclad sent, Bamford was behind him and would have had a tap in (albeit offside). Again, I'm not blaming him for conceding, I just think he has mobility issues and it shows up with har far away he can be from the ball when it goes in.
While I'm at it, it's a bit annoying the commentators reckoned if Bamford had tapped it in it would have been offside - you could argue that Bartley put his foot out *because* Bamford was behind him so I'd consider that interfering with play.