Starchy foods like grains, peas and potatoes aren't suitable for your dog.... or you for that matter.
Dogs do have the ability to digest some grain content and can include a small amount of grains in training treats.... but try as much as possible to limit their use.
Starchy foods cause your dog to continually produce a hormone called insulin.
This causes him to store a lot of food as fat, so if your dog is on the chubby side, avoiding grains will help.
This can lead to insulin resistance and diabetes,
but the biggest reason to ditch the starch is that it only adds calories to your dog's diet. While your dog would die without protein or fat, he has no need for starch or carbohydrate. Eating too much can disrupt the colonies of microbes that live in his digestive tact. These little bugs make up most of your dogs immune system and even help him produce vitamins.
When they're disrupted... your dog can suffer from allergies, yeast, and inflammatory health issues. In a nutshell, if your dog doesn't need them, why would you feed them?
There's no benefit to starch and the risks outweigh the benefits.
The only benefits to starch is it keeps costs down for you... they add no benefit to your dog whatsoever.
Most of the health benefits of the raw diet aren't necessarily because it's raw.. it's because every other diet is high in starch!
This is the main reason people see so many healthy changes when they switch their dog to a raw diet.