Defending requires discipline but also - there’s that old adage - you defend as a unit, which you’ve described above.
I can only think of two back lines that I had confidence in at Spurs…
Walker - King - Woodgate/Dawson - Assou-Ekotto
Parker screening
And
Walker - Alderweireld - Vertonghen - Rose
Dembele screening.
Not everyone will agree with the above, but we have rarely been renowned for good defending in my time as a Spurs fan.
I felt those back 4s, particularly the latter knew what their jobs were. Funnily enough, Walker is in both.
At the moment, despite what could be said that is good about our back 4, there is a lack of discipline and attention and togetherness at times and we really do get punished when that happens.