Any time that the skin is penetrated by a sharp object, ANY type of needle or scalpel, extraordinary care must be exercised. It is not only an opportunity for infection, but the practitioner is altering blood flow, a person's essence and chemical make-up. Without the essential knowledge of the interactions between the primary organ systems and how the systems (heart, kidney, intestines, spleen, stomach...) support or counteract, there could be unintentional consequences that neither the patient nor an uneducated practitioner would anticipate.
I respect the field of sports medicine. However I don't know about the expertise of athletic trainers. I would suggest that the educational requirements for trainers needs to be reviewed and analyzed for the surgical aspects that is dry needling. Even physicians who perform acupuncture are aware of the consequences of penetrating a patients skin in order to alter a condition.