Based on a lot of the sources that I refer to for baseball, the upside of Clark is higher than either Crews or Langford.
In Clark, you are really drafting a guy that allows you to kick Greene to the corner, a guy who can be a legit leadoff type bat who will hit for average and grow into 20+ homer pop, will be among the league's best defensive center fielders due to his athleticism and arm.
And regarding timeline, Riley Greene, who was not as highly regarded of a prep prospect, was drafted in 2019 and made his debut in 2022, despite missing all of 2020 during the pandemic. While you can't plan on it, it wouldn't be unheard of if Clark ends up on a two year track if he's as good as he profiles. The gap between Langford and Clark in terms of readiness is probably smaller than people choose to believe.
I do appreciate the defensive aspect when it comes to Clark, especially juxtaposed against Langford, who will be a defensive liability. Based on what I've read, I still think Crews has the highest upside of all 3 though, or is at least the same as Clark (but is further along developmentally). But if we get a Corbin Carroll here, I'll of course be thrilled, regardless of what the other guys do.
My main worry is just that there is more room for things to go wrong with Clark, not so much that he will likely take longer to get to Detroit than Langford. Clark's not been tested against as good of competition, and has yet to hit against high velocity. I'm not trying to drag him down, as these are only concerns and not criticisms of his game. He's just more unproven. But I am more in love with the upside today than when they made the pick. "Toolsy" gets overused in the sense that so many "toolsy" guys flame out as nobodies all the time, but there does seem to be some legit projection in this case.
This isn't egregious, like taking Jobe over Mayer, which looked stupid the second it happened, but I just have some concerns. Hopefully Clark assuages them. Risk mainly having to do with age and low quality of competition aside, I have no problem with the player. And while I think Greene is a more legit CF than may give him credit for, I do agree and love the idea of having two young, excellent defenders in the outfield who can also hit. Gives you more option with the 3rd OF spot.