The bags are 1.5"X1.5"X5", very small to grow anything, however, the trees manage to grow in these little bags which are coated with a copper compound that kill roots. So, how is it the trees don't die? As the trees start to grow, they put out roots which grow away from the main root. As each root reaches the material on the bag, the root is severed at that point by the copper. The part of the root that is in the bag continues collecting nutrients. The tree senses that the root has been truncated and makes more roots to replace the one that is not working to it's full capacity. That cycle repeats many times and the little tree ends up having many thousands of very thin roots.
Under those conditions, when you plant one of my trees, there is no reason why it would suffer from shock, every root the tree ever made is within the bag. When the tree is taken out of the bag, many of those truncated roots will start growing again, full speed, giving the tree a quick boost in growth. Be sure to water your trees right after you plant them.