I can't find any details on the makeup of the sa-11 warhead other than weights, no frag sizes, expansion rates and patterns, etc. But in reading about HE Frag warheads in general it seems the larger more or less uniform and heavier frag pieces travel further at higher sustained velocities than much smaller pepper and small sized, lower mass projectiles. The speed of the small low mass bits falls off quickly.
The center window section that's burned seems to have a lot of much smaller penetration holes. I'm wondering if that could be bits of the warhead casing that are smaller than the main frag pieces. If this is the case it would suggest that the detonation would have had to be really close since the tiny bits still had enough speed and energy to make holes in the center window frames.