This year's top 100 MLB prospects list is unlike any other, and it's for the reason you're probably thinking of -- there wasn't a minor league season.
Players certainly improved from last year, and there were trades, a draft and an international signing period, but there isn't as much movement because there isn't anywhere near as much new information as I'm used to having.
Much of what did happen was seen only by a player's own team (so I'm hesitant to take the club's word for it), with some sharing of alternate site video/data and some rival scouts at fall instructional league, along with prospect-eligible players playing in the big leagues. I'll note when there's a real piece of new information that moved a player, but assume until I point out otherwise that it was some version of "largely stayed healthy, appeared to get a little better (as expected), didn't play in many if any 'real' game situations, so we'll see next year if these observations were correct."
The Future Value (book on sale now!) explanation is the same as last year, but I've added Present Value as a concept for the top 25 prospects to measure how good a player would be in the big leagues right now. I'm making a concerted effort to illustrate the gap between prospects and actual big leaguers this season, so consider this an appetizer.
Here are the top 100 prospects in baseball heading into the 2021 MLB season.