Look at this photo of the fuselage of Commander Abhenandan's Mig-21 -
What's the first thing that you'll notice?
-- It's squashed flat.
Why?
-- Because it fell vertically like a falling leaf corkscrewing to the ground. The force of the landing from a vertical fall squashed the whole fuselage flat. But because the plane fell vertically (as apposed to a shallower emergency landing angle) its nose section remained intact.
This squashed state of the Mig-21 is consistent with the way it corkscrewed on its vertical descent in these videos of the crash:
Video #1 - Taken from location most likely at the rear of the Mig-21 or at an angle from the direction where the Mig-21 came from. This could be from the Indian side or from the Pakistani side right at the border with the Indian side. This video captured the moment immediately after the Mig-21 was hit and started falling. Notice that the plane was still able travel at a steep angle before the pilot ejected. But after the ejection the Mig-21 immediately started on its vertical corkscrew descent (it completely lost lift).
Video #2 - Taken from the opposite direction deeper into Pakistani territory forward of travel of the direction of the Mig-21. This video was taken on the lower half of the fall of the Mig-21 when it was already falling vertically on corkscrew.