This is a fairly common shoulder lock that I see a lot of people use at the lower levels. It's not necessarily a low level move, but an experienced grappler will keep their arms, in addition to their elbows, tighter to their body and make it difficult to get this.
With that being said, when you combine it with other attacks and use proper spacing concepts it can be a fantastic submission. I really like this submission because it is low risk. If you fail at this submission you are most likely going to still be in side control, North/South or Turtle top (if you miss the arm and they belly down).
Make sure to watch in the video (at the 2:10 mark) to see how I left my hips to cover the space and stuff the arm. This is a very important aspect that a lot of people miss. I see some people with great pressure that do not lift their hips and try to do all the work by stuffing the arm with their hands. By lifting the hips you can get to the wrist even if your opponent is strong!
This video is hosted from www.youtube.com