I think the situations you guys are describing are due largely to bank angles at low airspeed and PERCEIVED changes in altitude as the plane traverses the landing pattern. Gravity always pulls in the same direction (toward the planet). When you bank sharply, the plane's lift vector (which may be already marginal) is now operating at an angle, and not directly opposing the pull of gravity. Also, as the plane plane turns upwind, its perceived rate of descent increases as the ground speed decreases, so often the pilot instinctively pulls more UP ELEVATOR, which kills more speed, and suddenly gravity takes over. Anytime I lose the engine on a flight, I keep mentally repeating to myself "nose down - wings level". In the old days, some of my pattern buddies used to kid me about being banished to the sailplane competitions, as I seemed to have an ability to really drag the plane back to the runway on deadstick landings. I still remember a couple of new pattern birds that "fell out of the sky" during my early days!

Gear up, and on the pipe!