Chuck,
An aircraft in a sideslip (foreward slip) is flying out of balance. One can determine this by the fact that the balance ball is out to one side.
If the ball is out to one side then there is a component of yaw present.
Stall + Yaw = Spin.
When flying out of balance, extra drag is created. If power is reduced then speed will reduce quicker when out of balance then when flying in balance due to the extra drag.
If you are flying a crab approach in balance and transfer to the wing down, extra drag is created which will slow the aircraft and if the initial approach was at 1.3Vso then you can quickly find that you are below that speed at a low height with the ball way out to one side. Flying initially a few knots above 1.3 Vso should have the speed settled at 1.3Vso when the wing down is established.
DFC