I get that too: Elbow is below shoulder height, hand is close to or above elbow height (if only when reaching to change gear, rub your nose, whatever) so water entering the sleeve at the cuff doesn't get further than the elbow. Then you indicate...
Different steering arrangements are likely to exacerbate the effect. The Red Baron isn't a wet weather bike, but on the odd occasion I've had to wear a waterproof jacket, it's collected water in all sorts of odd places.