All radars, including fire-control, would have had their tapes...

All radars, including fire-control, would have had their tapes running, and Russian techies would be poring over them and putting things together. They'll work it out. The plane was out over the ocean, so it could have been hit by an incoming Froggy missile? The Israelis generally attack via Lebanese airspace.
The aircraft had its own radars and maybe took violent evasive action to avoid Froggy cruise missiles and stacked it?
They'll work it all out from the tapes.

GZ