If you want to hit it out of the bunker with control like Bob Krause, then you need to have stability in your legs especially the inside and outside of your thighs.
Here is an exercise that will help create strength in your legs that will not only give you stability for the bunkers, but for the rest of your game as well.
Do 3 sets of 10 2-3 times per week.
To see the complete workout program, go to ProGolfFitness channel on YouTube and checkout the Strength for Bunkers video. Subscribe to ProGolfFitness channel and stay up to date on golf fitness videos.
Strength for bunkers