I was watching Ship 41 come in on Flight 14.
In the last part of the belly flop, just before the flip and burn, it was dropping at about 100 metres a second. That’s roughly 360 km/h, still falling sideways.
If that had been a crewed ship and the engines failed to relight, a belly landing in the ocean would not be survivable. 100% a splat factor.
The whole landing depends on those Raptors lighting on time and flipping the ship upright. Sure, it can lose one engine. If none of them light, there is no backup.
Just watch the altitude meter drop.