not really, usually players are called up in their early 20s giving teams control through most of their early primes.
They're called up at 23-25 because that's when they're ready.
Harper, Trout, Fernandez, Machado, Xander Bogaerts, Teheran, Simmons, Heyward, Bumgarner, Stanton . . . all called up early/young.
Harper was ready. He was called up. He proved he was ready by winning RoTY. He's going through struggles like all young players do (I guess we're forgetting Anythony Rendon went like 2-49 at one point this year). He's still working counts and getting on base. The power is slowly returning. In a month, y'all are going to be talking about how great he is.