[StorminZ]

Here's something for you to consider. I know it's not quite like the other logos you referred to, but maybe it will do the trick ... your call.

FYI, the colour selections could be rationalized as follows ...

... green ... what I saw of Michigan (visited there last summer) was certainly "green" ... the parts I visited -- including the Upper Penninsula -- reminds me of northern Alberta, where I'm from.
... blue ... lotsa water surrounding the state with the Great Lakes and all!
... yellow ... baseball is a summer sport ... lotsa sun!

Not sure when you established your League ... the date is easily editted.

I have the graphic in vector format, too (for scalability).