Even though he went to college for 3yrs, he was only 21 when he entered the NBA. Fox was 19, and turned 20 in Decemeber of his rookie year. As you said, Fox has another year before he's at Steph's rookie year, but can he match up to his rookie year?
Buddy and Bogdan are old rookies.
Ok, let's break down the Warriors 5 then. Let's start the year when Draymond and Barnes were rookies. That's 2012-2013.
Stephen Curry: 22.9pts 6.9asts 4.0rebs 45.1/45.3/90.0
DAVID LEE: 18.5pts 11.2rebs 3.5asts 51.9/0/79.7
Klay Thompson: 16.6pts 2.2asts 3.7rebs 42.2/40.1/84.1
Harrison Barnes: 9.2pts 4.1rebs 1.2asts 43.9/35.9/75.8
Draymond Green: 2.9pts 3.3rebs (barely played)
Since you say you need 5 players in your core, then this was the start of their "core" since they just drafted Harrison Barnes and Draymond Green. We have any players on the team who can put up those stats?