"England's strength is in their middle order" is a bit of a myth.
In 2019
Buttler: 4, 26, 1, 24, 67, 56, 1 and 5
Bairstow: 12, 30, 52, 14, 2, 0, 0, 8 and 6
Moeen: 0, 0, 60, 4, 13, 0, 9 and 0
Either out of nick or not up to it. A combination of the two I would say.