...and Franco and Witt and JRod all gave the team consideration for pushing them to the majors. ...and Wander Franco was disappointing in his second season. Whatever difference there is between play A and Holliday AT THIS STAGE is likely modest, if any. That doesn't speak to what he'll eventually be.
Ther's a lot of Monday morning QBing going on here. Holliday wasn't considered a consensus #1 pick. Last year he had a crazy walk total (135) and apparently (I don't know the numbers) the exit velocities were good so you have a young guy doing well. ...I have zero issues with projection, but what level was he doing something crazy? A-ball doesn't really count. They let him move through quickly. Cool. AA was .928 OPS which again is good (only 162 ABs) and he gets a cup-of-coffee (.796) with Norfolk to get him into the Playoffs?
Again, I'm ok with the projection, but most all of the hype is a couple months at AA. Are you seriously making a Trout comp? Trout has been one of the best plyers in the history of MLB. Maybe we should slow that roll some?
Why wouldn't I make the comp with every prospect that's been a top-1 or top-2 prospect and hitting the majors at age 20 or under, including Trout? That's the ceiling for prospects of this caliber, at his age. Is he likely to hit that ceiling? Of course not. But his career to date fits the profile of someone who might. And it's not like trout is the only one that had a 5+ WAR rookie campaign. Machado and Harper both did as well. Plus, some of the guys I listed had worse minor league stats than Holliday at the same age. Machado was called up as a 19 year old in AA, and he had a sub-.800 OPS at the time.
Franco's 2nd year he got injured and didn't play a full season but was on pace for 4+ WAR. His 3rd year he put up over 4 WAR in only 3/4 of a season before the scandal hit. These things never account for injury but he's lived up to his hype as a player when he's been on the field (albeit not as a human being.)
His draft position is irrelevant and prospect valuations are far more predictive of future production than draft status at this stage. And he's a unanimous #1 prospect with multiple 70 overall FV grades. At his age those kinds of prospects are the kinds you start early HOF watches on.
You're right that the error bars are decently large when trying to project major league performance based on scouting reports and limited minor league data. He might be Witt Jr. And take a year to get acclimated. He might be Yoan Moncada and never live up to the hype. He might be Jurickson Profar. Or he might be Machado/Harper/Trout. You have big error bars with any prospect but you definitely don't have HOF level upside with any prospect.