sometimes you get spillovers/drips. those pans are more trouble than they're worth. if washer floods the pan won't hold it, depending on washer/floor/use etc, it can cause shaking/out of balance,and if you need service,chances are pan will get broken.
My two cents worth in on this one, if you please. Some eight (8) years back I had some type of seal in my washing machine go bad and water got all into the laundry room which was next to the master bedroom with carpet, etc. Yes, I put on a load of clothes just before I left for work in the early A.M. and it happened before I got home. A complete new laundry room floor, new carpet in the master bedroom, drywall repair of the common wall between the two rooms and an exterior wall. Homeowners insurance did not pay for it, large deductable. After that episode I went to a local sheet metal shop and had them make me a four inch deep pan to place under the new washing machine. I put me a drain hole where I wanted it, soldered a one-inch copper tube to it so as to run out under the house and the exterior wall, in case of a leak. I just don't want to go through this again. My story, David