For what it's worth, consider the curious case of Devin Booker. In his 1 season in Kentucky, he averaged 10ppg/1.1apg/2rpg in 21.5mpg. With those numbers, you wouldn't think twice. Solid, but unspectacular, dime a dozen. Good, not great athlete.
Then you look at his 47%fg, 41% 3p% and 83%ft shooting and you start thinking that this guy is a really good shooter... maybe he can be a 3pt specialist in the NBA. Can't be a 3&D player cuz he's not athletic enough.
Four years after being drafted #13 overall in the 2015 draft, he is averaging 24.7ppg, 6.7apg, 4rpg in the NBA in his 4th season. He's arguably the best player of the vaunted 2015 draft class that included KAT, Russell, and KP. Last summer he signed a 5yr/158m contract.
College numbers aren't often indicative of NBA success... though if a player's already a good shooter in college, it generally is a good indicator that he can find a role in today's NBA.
Now back to Barrett. He's a guy that looks like the total package... he's probably more advanced than Booker at all skills, except he's not a great shooter. They say he has a flat, albeit improving shot. What he does have going for him though is that he has a great sense of space around him, he flashes legit PG skills and has a lot of deception to his game, a lot of that euro-step lefty thing - perhaps a good comparison might be Manu Ginobili. Or how about Lonzo Ball with a more conventional shot? Or a lefty DeRozan?