I read that article and felt that it was a bit odd in its' description of bending excersizes, but what I watned to ask was, is this a gaited horse? Because the article is talking about suppling gaited horses, who can often become remarkable stiff in the back.
Really bending a horse in the way you are wanting, ( to improve the horse's balance under saddle) means that you must have the bend go all the way through from the bit/poll to the hind end and feet. So, just having the horse bend its' neck around and tough its' nose to it's shoulder is not going to make a big change in its' way of moving. This kind of bend might be nice for a start, but done incessantly (as some NH training regimines do) will make a horse with a "rubbery" loose neck, with no connction to the hind end.
Oh, but that's another rant.
So, what I meant is that bending trhought the body is evidenced ultimately by the inside hind end stepping under the horse's midline, and well in front of the outside hind. But doing this, it makes the horse's barrel swing outward which creates the feel of him bending in the middle part of his body (where is is actually virtually impossible for him to actually bend those vertebrae), That stepping, barrel rolling, lifting of the inside shoulder, gently arching of the neck with the poll at the top and flexing at the jaw such that the jawbone kind of tucks into the throat and the face stays vertical (not tilting sideways) is the vision of bending that you are looking to have.
So, do not leave out looking and feeling for that all important inside hind leg to step under when you do whatever bending excersizes you choose to do.
Thanks for letting me mini rant!