Bruce has learned absolutely nothing from all the spies and soldiers. He's been trying to learn basic self defense here, but his greatest stealth skill was his remarkable ability to be unremarkable. It was easier for him to hide in a crowd than most people. It's not his fault that Betty's so observant she can see right through anyone and anything. Maybe it's how she got through a household with a certain someone through her life.

Bruce throws all his snowballs in her general area but none of them land because she's behind a shed. He has to make a daring attempt to come closer, and he is feeling confident for about five minutes before he slips and falls right into a snowpile. So basically, he defeated himself. He very awkwardly attempts to get up, and then ... decides eh and tries to slide into pretending to make snow angels. Yep. That was intentional.