Makes sense, what do you market? Basketball and football highlight reals are entertaining displays of athleticism, baseball highlights are plaim boring
personalities are the only way. A-Rod was a perfect villain. Jeter had the ego, charisma, iconic moments and perfect timing (baseball is way behind NFL now). Griffey had his signature look. but that was a different time. harper has the perfect combination for marketing and he's basically the only MLB guy with any national presence right now. and he had a leg up because he was hyped at age 16.
IMO it's basically because since like the mid-2000s the NFL has taken over the national sports conversation and the NBA has slotted in at #2. There are tons of great players with personalities in baseball but it's just a regional sport now.
i honestly forgot MLB was playing yesterday and i don't even watch the nfl