I honestly don't remember if that's the case with the blend. I remember the more blend I added though introduces more of the era knobs character too so keep that in mind. They all work in conjunction with one another pretty well. Check the manual for more on that blend though. Here's the excerpt from it: (you are correct in your statement)
Controls
Blend: Mixes the clean input signal with the overdriven signal. The clean signal remains at unity gain while the volume of the overdriven signal is set by the Level knob, allowing for fine control of the blend ratio.
Era: Interacts with the Drive knob to shape the character of the pedal. Dial it down to get the warm midrange tones of the 70s or crank it up to get the punchy metallic tones of 80s and 90s rock.
Level: Sets the volume of the overdriven signal.
Drive: Sets the amount of saturation in the overdriven signal.