Factors that seem to affect my lawn cut quality:
1.Deck design - deep or shallow deck
2.Blade design/sharpness - 30 deg is what I like
3.Ground speed - typically 3-6 mph
4.Grass type - fescues or buffalo grass
5.Grass height - finish cut is about 3-1/4" measured on level concrete with a genuine plastic JD blade height tool... /forums/images/graemlins/smile.gif
6. I find that identical blade height, front to back works best for me on my RFM. Your MMM might be the same. In a sense, the grass has a chance of getting cut twice, once in the front and once on the back. (FWIW, on my the Bush Hog rotary mower, the front is about one inch lower than the back...just cuts faster, but not cleaner, but that is cutting 2-3 ft prairie grass/brome).
Lastly, I find that the best combination is to use OEM blades on an OEM deck. For example, with my Landpride rear finish mower, I always use a Landpride blade. Anything else is awful. And my JD lawn tractor has the BEST cut with NEW JD blades.
Are you using kubota blades on that MMM? Are they new or old? Try a set of brand new blades and I bet you'll be pleasantly surprised at what a terrific cut you'll get!
Best of luck!