go south

"It was great. Everything was perfect, right on track."

And they have cycled back around to the most formidable portion of their rotation, with A.J. Burnett and CC Sabathia set to start on back-to-back days.

Chamberlain pitched well -- except one major hiccup in the third.

You can refer to a small problem or difficulty as a hiccup, especially if it does not last very long or is easily put right.

Girardi did not do so Tuesday, either. But he did offer a crumb.
A crumb of something, for example information, is a very small amount of it.
At last Andrew gave them a crumb of information...

There is NO medical or scientific evidence that this arbitrary innings limit will prevent Joba's arm from going south.
go south
AmE informal if a situation, organization, or set of standards goes south, it becomes very bad although it was once very good