It's not particularly good as a predictor of injuries but allows you to look at possible sources of weakness that can be worked on with a view to decreasing risk. Quad/hammy ratio is important for ACL risk reduction, bit less so for hamstring strains. Any professional team should have this sort of kit in their biomechanics dept and will use it to monitor players for their normal ranges for use in recovery, and also to address any asymmetries like mentioned in that story above. You'd think he'd have got this tested before spending the cash on the acupuncture etc.