One of the ways Furudate writes hope and realism together in Haikyuu!! is by making clear that victory requires sacrifice. What that looks like for our main character, Hinata Shouyou is highlighted at the end of his long detour to professional volleyball, during the Adlers vs. Black Jackals match.
The narrative during the Adlers vs. Black Jackals match highlights that for both Hinata and Hoshiumi, it’s not enough to be great spikers, or even great spikers AND good all-rounders. It’s expected out of any player at the professional levels to be flexible and good at everything, but in order to justify substituting a short player like Hinata or Hoshiumi in for a taller player, they must also be expert receivers, blockers, and setters in addition to jumping even higher than tall players.
The Nationals match of Karasuno vs. Kamomedai was a preview of this particular requirement, Hoshiumi and Kamomedai wins that match because Hoshiumi had already begun to put the work into becoming good at every position. He understood that it would be required of him. Hinata who had a lot less experience at the time, hadn’t understood that yet.
At that point, the narrative doesn’t say it outright but this hidden requirement is further solidified by Hinata’s decision to go to Brazil and play beach volleyball — a sport in which you must play every position. Sometime between the match against Kamomedai and that conversation with Tsukishima in their second year, he had come to understand what was required of him and found a way to do that.
Hinata sacrificed playing indoor volleyball (temporarily), in order to gain the skills he would need to be successful. It was a detour but also a shortcut, because the high demand in 2v2 beach volleyball would force him to develop those skills faster than he otherwise might have.
Only after two years of beach volleyball was he able to come back to Japan and make his debut in professional indoor volleyball. Only then had he earned the right to stand on that court, across the net from Kageyama.