Every player has random opponents that owned them. These are Mickey Mantle's.
Mickey Mantle was very good at baseball. Obviously. But the thing about baseball is that when you get the sample sizes small enough, you can find weird things. You can find pitchers that you've never heard of that Mantle weirdly couldn't hit.
In the final five years of Mantle's career, the Tigers had a pitcher named Joe Sparma. Sparma made his debut in 1964 and had an okay season. He followed that up with another good year in 1965. Every year after that, his stats are below average.