I suppose it could also be explained by the fact that the crew at least thought that the runway was slippery and did not start using full braking power immediatelly to avoid an hydroplanning
Just to say in respect of this one suggestion (because I will not comment on the crash or it's causes until the final report is out):
Hydroplaning (or aquaplaning) will occur regardless of brake application - it is a function of tyre pressure, speed and depth of water. The relevant point is that if the criteria for aquaplaning are present then the application of brakes will be very ineffective; the application of braking does not in itself cause aquaplaning.
Regards
Exeng