I was in my tae kwon do club today and suggested 'let's grapple' to show that the locks that we are being taught standing up still work on the ground and three guys accepted the challenge. All three were far less experienced than me (black, purple, and yellow belts,) and had absolutely no grappling experience, but the first two each outweighed me by 70lbs or so.
Anyway I noticed that once I set a trap they fell right into it. The blackbelt pulled one arm out of my high guard to try and push me off and I pulled a triangle choke, I got one of the purple belts arms in between my legs and he stood up, making the arm bar easier, and the yellow belt gave me his back when we went down allowing me to do a rear naked choke.
I suspected that they would fall into traps like Gracie had designed them but I was unprepared for the difficulty of actually setting the traps. Because they didn't really know how to handle themselves they thrashed around and tried some unorthadox choke attempts and I had a more difficult setting them up that I do against an experienced judo or ju jitsu player.
Just something to keep in mind if you ever had to take someone down, you are used to grappling someone who doesn't panic and knows how to smoothly transition, so they will not fight like you will be expecting them to.