I'd say the entire second half, to be honest.
Then I'd say maybe you had unreasonable expectations of the role he's supposed to be in. Out of 10 second-half starts not counting today, he's had (by my judgment) 5 good, 4 bad, and 1 acceptable (6.1, 3 ER).
So again, I guess it revolves around your definition of "good" and what you were expecting from a ~40+(?) year-old junkballer. Unless you weren't watching you should already know that some of his bad starts were bad enough to make his overall numbers look worse than his game-by-game performance has actually been. I don't think there's a soul on this site who didn't know he was playing out of his mind for a lot of the first half.