That being said, when I do hit the straight ankle lock, I've found using a grip more like an RNC grip provides more control, torque and ultimately leads to more submissions.One thingI have noticed is that the ankle lock where you simply clasp hands/latch the free hand over the hand trapping the foot/ankle in the armpit has not proven as successful for me in rolling.
Regular Straight Ankle lock Grip: note the foot in armpit, and typically the hands will lock together. In the picture below the left hand is grabbing the lapel, and the competitor will over then grip his left hand with his right hand. then go belly down and apply pressure/curl the foot and toes back.
RNC-style Grip -
When possible, I get almost a full RNC grip where my arm locking the ankle into the armpit actually grips my other bicep.
While we're on the Straight Ankle Lock, a short seminar style video about the ankle lock is here by Lucio Linhares, former UFC fighter.