Some rookie things...
After a rough month, Duran appears to be adjusting back. He's only struck out once in his last 17 PA while taking three walks (if you stretch it back another 10 PA, that's four times in 27 PA). His OBP on the year is .350, his OPS+ is 112, or about even with Devers. Hi BABIP is an astronomical .397, though, definitely unsustainable, even if he's hitting the ball hard 45% of the time and line drives 30% of the time. The BB% is 8, or around Verdugo and just south of Masa and Turner.
To my eye he's still a clumsy fielder, but he's getting much better jumps than he did in the past. He's still striking out 28% of the time, which is a lot, but I think the optimistic case is he cuts his K% about 2-3% over the course of the next couple years and ups the BB% by 1-2%, improves some more in CF - that's a 2-4 win player a year. The pessimistic case is he regresses defensively and offensively: the adjustments he's making in strike-zone judgment are transient, he doesn't improve anymore defensively, his BABIP rounds down to a reasonable .333 or so, and he turns into a guy who OPS's between .650 and .700 each year and steals some bases - that player is still worth a win or two. I'd guess he's somewhere in the middle, or has some years when he's the former and some where he's the latter.
The three rookies -- Casas, Wong, and Duran -- are still at the bottom of the team in terms of K%. Wong is at 32%, which is dangerously close to Cordero/Dalbec territory... but he's a catcher, so it's a little more forgivable. I'd like to see him go on another tear, but I think a league average hitter is what we should expect, which is a boon at his position. Duran is at 28%, which is not great, but he makes hard enough contact when he does and is walking at a good enough clip for that to be acceptable. Casas is obviously continuing his climb out of the cellar. He's putting together great at-bats, striking out less, and getting jobbed by umps (like he did last night).
They're an interesting cast of characters. Affordable, potentially above average at their positions, but not definitely, and not stars by any means. Casas will have to hit better, Duran will have to sustain this performance, and Wong will have to keep his whiffing under control.