I don't mind the Sox trying any of these guys, but Duran needs to play every day, no matter what level he's at.
I watched that Woo game that Duran won on a walk-off HR. The Pigs walked Cordero intentionally to get to Duran. Yes, it set up the DP with the automatic runner on second, but they didn't want to face Cordero -- Duran isn't a groundball hitter, but he had Ked three times... Still, gotta like him driving the ball oppo to win it.
History has seen young prospects get called up to the bigs and improve with hot starts, while others fall cold. There's more pressure and tougher competition, but many factors also favor performance: better travel conditions, meal money, training facilities, playing field/lights resulting in better rest, nutrition, conditioning and conditions. Seeing more strikes to hit with (hopefully) better umps can also help... or hurt.
Duran has 12 homers in 30 games. At that pace, if they leave him in Triple A the whole season he'll hit 50 HRs. At what point will he be deemed ready for Boston? He's 24, seven years older than Bob Feller was when he was striking out major leaguers.