Thinking overnight this is suspended deck design. Many of the suspended deck design have replace that stiff plate with a simple adjustable rod where you can change the amount of pull that applied to the deck. I thinking more like suspension bridge where the deck finds a happy place and floats around this point. Think of it like rope being held both ends with board in the middle. Shorten the rope one end and the board changes it angle as more weight is at the short side allowing the long side of the rope to raise up as it has less weight to support.
These decks tends to scalp the high points between wheel base and skip over low spots. It takes gauge wheels to prevent some of the scalping. This design works best on fairly level lawns and not ones with lots dips and bumps.
One good thing about the design though is not as prone to deck damage from hitting tree roots where floating design tends to get a lot impact damage. I know because this because I have own both designs. I spend a lot time repairing the floating front wheel brackets because tree roots.
