Add motion blur to footage with Smooth Slo-Mo in Final Cut Pro 10.8

Sometimes you get footage where the camera operator had the camera's shutter speed set too high, resulting in no motion blur in the footage which can make movements look "harsh" and "choppy", especially when shooting at 24 or 25 FPS. There's no perfect solution to this, since nothing can match capturing real motion blur in-camera. The solution that most people have used throughout the years is to apply digital motion blur to footage via, for example, pixel tracking - which is more or less the same technology used in Optical Flow and the new Smooth Slo-Mo feature. Can a clever Final Cut Pro user come up with an idea for how to use Smooth Slo-Mo to add motion blur to footage?