A trainer who helped me start my Brittany also owned one of the same age. This trainer was pushing everybody into raw feeding. She kept telling me my dog looked skinny but the truth is at that time he out weighed her slightly plump Britt by 3 pounds. Her dog also couldn't run as fast or keep up to mine. It would be simplistic to draw the conclusion that it was only food related but you also can't discount it. Both of our dogs have excellent pedigrees and breeding.
As for the level of contaminated commercial kibble vs raw I don't know the actual stats but my guess is the kibble produced and sold in North America is likely in the billions of bags. I doubt that raw would even be close to 5% of what dogs are fed annually. The more bags you sell the larger are the odds of some manufacturing defect so without a useful number to compare consumption of kibble vs raw quoting a few recalls really doesn't help making a decision one way or another. How many raw producers are large enough to issue a recall or have it recorded in the media? It would be like comparing the recalls of a Honda civic vs a Mercedes. With so many more in the field of one over the other the actual percentage of defect is not reflected in the reported incidences.