Generally, a prepositional phrase comes immediately after the word it modifies, so if it's after a noun, it's an adjective, if it's after a verb, it's an adverb ...
A prepositional phrase may be used as an adverb telling how, when, where, how much, and why and modifying the verb and sometimes an adjective. Adverb ...
Adverb prepositional phrases that modify adjectives and adverbs must go after the words they modify. Like intensifiers, they tell to what extent. They can also tell why or in what way or in what circumstances. I am hungry \ because of this diet. ( Because of this diet tells why I'm hungry.) You can run pretty quickly \ in those high heels.
Adverb phrases, in contrast, follow the verb. You are asking, in effect, how 'good' can be an adjective when it follows a verb, when that would be considered an adverb in a prepositional phrase. The reason is, "good" is not a prepositional phrase. It is simply an adjective.
Sometimes a prepositional phrase could make sense either as an adjective phrase modifying the noun before it or as an adverb phrase modifying the verb. In this ...
Prepositional phrases can function as adjectives to describe nouns or adverbs to describe verbs. Students are asked to identify the prepositional phrases and ...