If a company is sponsoring a runner just for brand awareness with the masses, especially a runner who isn't at the very top of the game or some social media darling, they aren't getting the return.
But there is so much more to bringing elite runners into your company than brand awareness for the masses.
First of all, there are 600 running stores in the country and a portion (even if it's just 20% of them) of the owners and footwear buyers at those stores do know and care about the sport. They hold a ton of sway for what shoes are sold in their community.
Those stores might feel they want to carry a 2-3 carbon plated racing shoes. They might not be able to get their hands on the top Nike shoes, so they have to choose from other brands, and they know/like some athletes that most of their customers have never heard of. Which leads to Saucony on the feet of the local runners in the store's training group because Jared Ward validated the shoes for the store owner, if not necessarily the end customer. Even better is if Saucony is able to send Jared to one of those training group runs to talk with the customers.
Second, marketing is only a small part of what shoe companies do. Actually making the shoes takes up so much time and resources. Having elites test those shoes is invaluable for the product developers as they make decisions that they hope will be on the feet of countless runners. This is why the Brooks Beasts are in Seattle and spend time at the Brooks HQ regularly.
Third, Brands have a never ending need for content. They need pictures and video for catalogs, their website, social media, store posters, trade show booths, billboards. The needs are endless and span the globe. Of course they can hire random models or recruit their friends to take some photos, but they can and do also use their sponsored athletes.
Fourth, these brands host high school races and camps. They have pub runs and sales meetings with key stores. They have charity functions. They have executive retreats and board meetings. If a sponsored athlete can appear at those and impress the people there, that can be valuable.
So if it's all about getting the logo on a chest and hoping people see that logo, its not worth a whole lot. But there's so much more potential.
In the end, sponsoring athletes is actually a pretty good deal for the brands that do it right.