Hi, Joe. I can screw up my crosswind landings even without anyone to help.
Hard to say, if he isn't talking. May not have held ailerons into the wind; may have ground looped; may have applied brakes so hard he upended (difficult on sod because of less traction); may have hit a hole; may just not have been his day to fly.
If he was used to making soft-field landings in a tricycle gear, he may have been holding nose high from old habit, and then maybe over corrected. God knows I make mistakes on almost every landing. Happily, S/He's not telling the FAA that news.
A couple friends of mine have sod fields near here. I land at one (wide open, except wires at E'ly end), but not the other - too tight a runway for me. It's an uphill/downhill runway. I think he takes off down hill and lands uphill, no matter what the wind is doing. I drive past it on the way to the field where I'm hangared, so I'll just drive in to see him.