The drop in pressure gradient is a lot more rapid on the left side of the 'vee'...per axial distance than on the right side...Or, depending on what is happening, the drop is pressure gradient is a lot more rapid [on the left] than the recovery [on the right].
It also appears you might have a lot more data points on the right that the left of the 'vee'.
You can draw a straight line throu each side of the vee and from that estimate the slope [rate of change] during the middle phase of each.