There's some luck involved, Franco was developing into a solid 3B, with a big half season at 22 and respectable at 23 until he lost his mind (well, at least the ability to hit).
Hernandez steadily improved until he didn't, that is, his 2016-17 seasons, instead of setting his baseline, became his high water mark at age 26-27.
Galvis was always a stopgap for Crawford, and that was just a kid who never developed, and while his defense improved, his 86 RC+ and 1.3 WAR suggests they were right to move him. Now maybe he steps up, but I think 3 WAR is probably his ceiling.
But at the time, Franco - Crawford - Hernandez, with Kingery behind them, looked pretty solid.
Segura has his worst season in 4 years and still put up 2.3 WAR, a rebound and move to 2B could get him back over 3.0 again.
Didi buys a year for Bohm to arrive and fit in at 3B.
Then you have Bohm - Kingery - Segura - Hoskins, until Stott arrives in 2022?
Or you resign Didi for a couple years and move Segura.