The blade needs to be low enough so when the grass is being layed over by the baffle the front cutting edge can cut it, if too high in the baffles the grass gets cut further back on the blade edge. If the blade is to low it will force some of the air it is moving out under the baffle dropping the chamber air flows and discharge velocity. On the older decks the blade height (cutting edge to the top of the air foil) was split in half by the bottom edge of the baffle. The new baffle has the sections that drop down (these help lower the air turbulence between the cutting chambers from forcing air under the baffle) lower then the overall bottom of the baffle and the blades are set in relation to those two drop downs, which exposes more of the air foil below the higher part of the baffles lower edge. It isn't usually a problem in this set up for most users but certain conditions may require this relationship to be changed.