Horses in the stream 3

Growing dissatisfaction with the status quo can create a rebellious atmosphere. To break the monotony you might consider changing horses in midstream, but be careful you don't end up in over your head. (Detroit News)

So I'm rebelliously mixing metaphors? Though, I guess if you are changing horses midstream and the stream is kinda deep you could end up in over your head. But if the stream was that deep, would you really try changing horses in the middle of it? And why would you change horses midstream anyway? Why not just get across the stream then....

OK, just had to stop myself and google the origin of that phrase. This is from The Phrase Finder:

Meaning
Don't change your leader or your basic position when part-way through a campaign or a project .

Origin
From an 1864 speech by Abraham Lincoln, in reply to Delegation from the National Union League who were urging him to be their presidential candidate. 'An old Dutch farmer, who remarked to a companion once that it was not best to swap horses when crossing streams."

I still don't understand it, and suspect that whoever writes the horoscopes for the Detroit News is still all caught up in the Obama/Lincoln thing.