DBM is 100% correct on the oil flow (not that I didn't believe him).
I went and looked at my parts engine.
Look at the image. In yellow on the engine side is what I will call the oil pump outlet, and on the case is the inlet to the oil filter area. If you look at this and think about what is going on, oil has to flow this direction and it all makes sense. The oil pump outlet fits snugly into the corresponding hole in the case circled in yellow, which is of course the oil filter cavity.
See the red "oil path"
Oil goes into this little filter cavity under some degree of pressure, flows into the outside of the filter down through the center of the filter (now clean, filtered oil), then up into the little oil passage that eventually carries oil up to the top of the engine and (I think) to the backside of the clutch case where it spits out clean oil there too.
So, if you have a gunked up filter and oil comes shooting into the oil filter cavity under pressure it has to go somewhere.