Well, you're right and so am I. I was trying to come up with the answers without checking baseball-reference. The key to the question was that these were his only NLCS HRs. I think the Mets made it back to the post season in 1972, so that made it likely that it was a Brave. The most prolific HR hitter for the Braves at that time was Aaron, and it probably took a good HR hitter to hit three in three games since the Mets swept the Braves. However, most trivia questions aren't answered by the "obvious" anwer. I think Aaron started playing for the Milwaukee Braves in the mid to late 50's, say, about 1957. I know he was traded to the Brewers at the end of his career in the mid 70's. So, by 1969, Aaron had but 4 years left of what was to be about, what, an 18 year career with the NL Braves. I think that reasonably constitutes a "tail end". Although, I agree, the term "tail end" connotes "washed up". As you pointed out, Aaron was hardly "washed up" a la Bagwell was at that stage in his career.
If you want to persist in being right, go ahead. I didn't have to check the stats but to confirm my own memory. You see, unlike you lil whippersnapper, I saw Hank Aaron play. And he was no more on the tail end of a career in 1969 or 1970 1971 or 1972 or 1973 (that's five seasons, not the four in your math) than the man in the moon, when Mr. Aaron
averaged over 40 home runs a season during that stretch. If you'll check the league leaders for those years, you'll find that he was among the league leaders for each year during that stretch. he garnered MVP votes and was an all-star during each of those seasons. Hardly on the tail end, which was pure flapdoodle.
He didn't start slowing down until 1974, when he still hit 20 home runs. Even as a reserve platoon player, he still managed to hit home runs in double digits for 1975 and 1976. As I said earlier, Hank Aaron hit approximately 30% of his home runs after 1968.