Thwack

Checking out a new speed light. Portable unit packs a punch -- 360 watt-sec. puts out a lot of light. Lens stopped down darkens the daylight background nicely. Ball speed and racquet speed are faster than the decay of strobe, so even with rear curtain sync the gradual flash falloff produces a bright, somewhat "frozen" ball initially but continues to illuminate it as it moves forward. Same holds true for the racquet if you look closely. The streaks are in front of its initial, brightly lit position.

People often think of strobe light as "fast", when in fact it may take as "long" as 1/500 sec. or so to decay when fired at full power, as the case here. And there is considerable light energy produced during this time. So that's why very fast moving objects are not "frozen". The relatively slow 1/180 shutter speed doesn't come into play here because the lens is stopped down and the ambient light isn't illuminating the subject in any meaningful way.