Hi,
I'm seeing something weird in the ouline given out by freetype (2.5), when hinting is disabled (or set to the TTF's own & there's none), the geometry below the baseline seems to be shifted up by a tiny fraction.
My test is a font of 2048 units/EM, used at height 16, so that 128 units=1 pixel on-screen.
Above the baseline everything is perfect, but anything below is moved up by a fraction of a pixel, possibly around 8 units.