for me they make intelligent retreats. they pull out if its certain that they cannot win, but if they have a significant chance at victory, they'll take it.
Thats also my experiance after the new patch

They sometimes tryes to run thru my grav well, and heads directly to my main planet.
Not always the best option, as some of the AI ships will get destroyed, traveling thru a guarded grav well.
But i was surprised, how well the AI could calculate how good a chance, it has to win a battle. Cause i sent in a Dreadnaught and some frigat support. I also had another fleet (a kol and a few frigs) cleaning some systems from pirates. But i had the fealing i really need it, cause the AI really pumps frigats into one of my systems.
They destroyed my dreadnaught and a few frigats. Then the "kol" fleet arrived, and at the same time my carrier that was just constructed.
At this point i could see i was about to win, but so could the AI
I dunno if they changed anything to the AI intelligence, or its just because it cant phase jump thru a grav well anymore. But anyways, it has become smarter to my experiance. Though i havent tryed a longer game, so i cant tell if its the same in the endgame.
But IC keep up the good work