This is an excerpt taken from Responsible Sports for Parents site.
"Remember, research shows that athletes who receive positive encouragement, support and unconditional love from their parents tend to thrive."
A great website that I would encourage parents and coaches to join as it often addresses a wide variety of sports/situations/encouragement/suggestions.
Keep in mind also -- is it your child wrestling or is it you? You have "no idea" what it's like to be in their shoes or perhaps you do but they are not a mini you as much as you would like for them to be. If they give 100% Appreciate and Love that they gave 100%. Remember, "every dog has their day". (An old Cardinal euphamism).
And to that may all wrestlers wrestling this weekend TCOB!