The third landing of the B1051 booster was a hard landing but it was just within the safety margins the crush cores provide. The fall might have been caused by the drone being at the bottom of a swell or a last-second anomaly with the booster’s landing engine.
Above is a picture of the drone ship after the slightly damaged booster was removed
I went airborne to get a better look at #SpaceX #Falcon9 B1051.3 and #OCISLY. Here are a few shots, including a family portrait, the booster, and work being done on the OCISLY's deck. We all saw the hard landing, but is there damage to the droneship? I can't tell for sure.
— Stephen Marr (@spacecoast_stve) February 3, 2020