Usually the best time to hit the right straight to the body is when the opponent has their back to the fence. In this case Chairez hits Lacerda when Lacerda’s weight is on the lead foot. From this position, Laceda’s only defense is either to slip to the open side, lean back or the most effective one in open space: back up.
The great thing about the right straight to the body in an open stance match up like this is that even if the right straight misses, the opponent will have to give up space.
Chairez Right Straight to the body in an open stance matchup