I have never been one to put huge value on teenagers. You just never know what they will be like when they are playing against NBA competition rather than high school and college.
Tatum is young but has proven he has what it takes to be a star in this league. To me, being proven as being able to star in this league is more important than raw ability that hasn't been proven.
Markelle Fultz
Dragan Bender
Brandon Ingram
Jahlil Okafor
Mario Hezonja
Jabari Parker
Dante Exum
Cody Zeller
Alex Len
Anthony Bennett
2#1s, 2#2s, 1#3, 2#4s, 3#5s. All massive busts. All in the top 5. All in the last 5 years.
I will take the 21 year old that has proven he can be a star in the league before a top 5 pick any day. Even at the top of the draft, it's still a roll of the dice.