We have always had retrievers and as you might guess (duh), their job is to retrieve. Now... retrievers are not particular about what they retrieve--just give them something that they can call their own to get and they will get it.
Our dogs have used sticks, frisbees and balls as their item to retrieve. Brandy, the current occupier of the dog bed/throne in our home, looovves to fetch her ball. The midair catch is her speciality.
I came across this video of a smart pooch doing her job. She loves to get her ball and figures out how to get it even though she hates to swim...or perhaps swim in a yucky pool. I'd say she is up for the job.