It's a big wheelhouse

On a rerun of According to Jim, Larry Joe Campbell's character "Andy" just used the phrase I'm in my wheelhouse upon entering a carnival.

It's an interesting switch from the typical use where the thing in the wheelhouse is an object or task that will be acted upon in a way that illustrates the strengths of a performer. Like a baseball or an argument.

Used this way the wheelhouse is apparently a comfort zone or area of expertise. To be in your wheelhouse is to be in your element.

I can see sweet spot being used this way. (I've never heard it but there are a few Google™ hits.)

I find two hits for I'm in my wheelhouse and both are used this same way.

Here and here.

I find one hit for He's in his wheelhouse here and one hit for She's in her wheelhouse here. Both of these 3rd person uses are in reference to contestants on the current season of American Idol.

This is how idioms get started. Or in this case we see a metaphor becoming an idiom.