TJ.
What makes you believe that the bearing wears first,causing play thus allowing water in past the seal?
Surely the seal not being 100% water tight, water entering and causing corrosion therefore instant wear, therefore play is just as if not more likely.
I base this on the No. of cartridge bearings I have stripped due to partial seizing, where the lube is almost absent and corrosion has started. Cleaning and re-lubing with a waterproof grease resolves the problems for many hundred of miles.
For example, I fitted a new XT HT11 BB to my mates bike for a trip to Wales. 2 day's very wet riding followed by washing the bike (no jetwash) and parking the bike up for a week caused the BB to be notchy and horrible. On stripping, the bearings were full of rusty water and very little grease. The BB was cleaned re-lubed with Marine grease and nearly 2 years on is still runing fine with no further maintainance.
And before you suggest my initial poor fitting was the cause, I can assure you I am more that qualified to fit a BB.