Galchenyuk became the #1C while still 21, possibly a year too late, but not disastrous. Once installed, he produced at a high level, top 10 in the league. Even after he got hurt, and came back early, the coach who supposedly hated him kept him on centering our two best wingers. Go back to the last game Té Rien coached and you'll see I'm right.
Then Chu Rien came in and had to make a mark. He decided to throw Chucky under the bus, and MB went along.
Note that the entire time Té Rien was in charge he maintained that the goal was to have Chucky be the center, and he kept his word.
The shiny new coach decided otherwise the day he came in, and the GM did like he does with every other shiny new toy, which is give it undue reverence. The narrative changed from Julien's arrival, and Chucky was no longer seen as a center.
None of this means that Galchenyuk is a strong 2-way player, he isn't. But he could be sheltered a little playing alongside responsible wingers and with other better defensive centers already on the team.