To me the purpose of ThingManager is perfectly clear--to manage miscellaneous or common functionality that doesn't belong in Thing. In our apps we call it ThingService, and I'm sure other groups have a different convention.

For example, we're using a legacy codebase now where there is some complicated logic involved in managing attributes for products. ProductService is a singleton with no internal state that does things like removeAttribute(product, "foo") and serves other purposes. Before we introduced this pattern this kind of functionality was copy-pasted all around our controllers.

In short, I don't see the harm in this convention. Perhaps Manager or Service is bland name, but it's immediately clear to our developers what it does, and if you want to see if something has been done before with products, you look in Product or ProductService.