Not an expert here, but since nobody else is answering, I believe bottom is mostly trub (heavier stuff, settles out quicker) upper stuff more yeast. I think you're only supposed to let it settle like 30 min so only trub settles and you leave that behind, then go on to smaller jars, etc. Again, I'm not a huge yeast washing guru so maybe someone more knowledgeable can chime in.
Just wondering, why wash 05? Dry yeast = cheap and easy to get. Why bother?