It could be partially burnt out at the very least (how many strands of wire are in the Neu motors per coil? Maybe a strand or two is disconnected or burnt for some reason). Or if one or two FETs on the ESC are blown in one phase, then the motor would probably still run, but that one phase would probably cause issues on startup, but it would still be able to spin a decent amount of RPM under no load since not a whole lot of current at all will be drawn as compared to trying it in the truck on the ground.