I know grain can regulate digestive systems, by bulking up and that may affect digestion rates in the colon. I assume then if the kibble is grain free you may not have that problem.
Cats digestive tract is made for raw meat, right from the teeth to the large colon. The tract in a cat is very short compared to a human so digested food doesn't have as far to travel and doesn't stay in the bowels long enough for bacteria to build up. Plus the digestive tract has a lower ph which minimizes bacteria reproduction.
Jasper eats a bit of kibble (orijen) and raw meat and he doesn't seem to have any problems with it. He no longer has bad breath since I have cut back on his kibble and started him on Instinct canned and raw.