(v5r)to become decrepit; to be in one's dotage; to become dull; to lose one's astuteness; to lose one's touch; to become senile; to lose one's edge; to go downhill
彼の今回の判断、理解に苦しむね。焼きが回ったということかね。 I have a hard time seeing the logic of this latest decision of his. He just isn't as sharp as he used to be.