I have no memory of JT ever playing the SF position. If he did, it was a very bad idea. JT played center in college, and never truly developed the skills to even be a good solid PF. Tyreke's problem was his jumpshot. I never saw him as a SF but I did see him as a SG if he could become a consistent outside shooter. He finally has, and now is a legit SG in the league. Only took him about 6 or so years to get there though.
If we truly want to play this game, I can point out many players that changed positions in the NBA successfully, and I can point out many who couldn't. It's apples and oranges as far as I'm concerned because it comes down to the individual. What one player does has nothing to do with a different player. Klay Thompson played SF in college but plays SG in the NBA. Originally they tried to make Durant into a SG, but once switched to SF, he became the player he is today.
I learned my lesson a long time ago to never say a player can or can't play or do a certain thing. Because you don't know. All you can do is look at the players resources, and make a guess. There are people on this forum that predicted, after watching Buddy Hield in college, that he wouldn't be able to create his own shot in the NBA. Guess what, they were wrong!!!