How do non-externally baffled ridge vents perform?

Non-externally baffled ridge vents may allow air to enter the leading/windward side of the vent.

Non-externally baffled ridge vents may allow air to enter the leading/windward side of the vent and thus can pass air into the attic and/or through the vent to the downwind/leeward side. If this is occurring, the vent is only using one-half of its rated net free area at best. Also, if air enters a ridge vent it is possible that it will also bring in rain, snow and debris. Finally, a non-externally baffled ridge vent is also acting as an intake vent instead of an exhaust vent thus allowing possible cross ventilation.