Denny... Right on, I knew I was going out on a limb with those hypotheses - taking a moment at work - and basically scratching my head a bit. The issue of getting too hot too fast due to a high pitch I recall reading about and logically it would occur more easily for someone without good temp control. i.e. a factor that could make it that much easier for a ferment to get away from the zymurgist in the early stages. I know that I have read especially from Jamil about the importance not only of a sufficient pitch, but also problems from overpitching. Hence the desire to pitch "just right".
Anyway it all arose at my mis-reading the OP, who meant simply that he makes more yeast than needed and doesn't pitch it all.
So again the issue at hand might be tied to first, need for better control of mash temps, and bland or soapy flavor very possibly at least in part due to water chemistry and pH, and I don't recall if he efficiently treats for chlorine/chloramines.
I know that once I successfully negotiated the use of Bru'n Water (including selecting/creating the right water profiles) a lot of problems just went away and my beer definitely improved.