Subtitles have two usual uses. They can explain some phrase the author found particularly clever so potential buyers can know what the hell the book is actually about, or they can take their stab at helping to hype the book, most often in these cases promising more than they deliver.
To the second category assign "The Hero of Heroes," the pitch for John Rosengren's Hank Greenberg. The biography chronicles the ways the famed slugger for the Detroit Tigers served, too, as a Jewish icon. (A space in the public imagination he continues to dominate, if one notes the Mark Kurlansky Hank Greenberg bio of two years ago and this month's "special edition" DVD re-release of The Life and Times of Hank Greenberg.) His career was Hall-of-Fame worthy, with league dominating hitting; and his cultural impact was such that one of America's leading anti-semites, car czar Henry Ford, put aside personal distaste to enlist the batsman in moving more of his metal.
So, great player, good guy and aspirational figure? Absolutely. But H of Hs?. While inherently true about anyone famous that among that person's admirers are other admirable folks, it still seems just a step too steep to declare Henry Benjamin Greenberg. Hopefully it sells at least a few more books, nonetheless.