Each year, I keep track of some of the major publications and evaluators to determine a consensus amateur ranking. This should give you an idea where in general these evaluation sources agree and where they disagree. For the first edition, I have included Keith Law, Nick Faleris, and Baseball America. Keith Law is an analyst for ESPN and does his own scouting. Nick Faleris operates Diamondscape Scouting and contributes to an MLB organization. He as well does his own scouting. As I understand Baseball America's process, their list is more a compilation of discussions with scouts.
The following chart list the top 33 rankings, which is the same number of selections in the first round this year. The name rank from 33rd to 1st. In order words, players thought to be of higher quality are found lower down on the list. The extension from the bar is the standard deviation of the three sources, which indicates level of agreement. If a source does not rank a specific prospect in their top 50, I automatically gave them a value of 75 from that source. Only two players in the top 33 had to have ranks of 75th assigned to them (Taylor Guerrieri from Baseball America, Kolton Wong from Keith Law).
Finally, the sources date as follows Baseball America (February 3rd), Keith Law (March 22nd), and Nick Faleris (March 27th).
Based on these rankings, Bubba Starling is the fourth ranked player at 5.67. The following is a list of players ranked above Starling as well as those who are with one standard deviation of 5.67. Players are listed (with mean +/- SD) from 76 players mentioned among all three lists over the course of this draft season:
1. Anthony Rendon, 3B, Rice University 1.33 +/- 0.58
2. Garrit Cole, RHP, UCLA 1.67 +/- 0.58
3. Sonny Gray, RHP, Vanderbilt 4.33 +/- 1.15
4. Bubba Starling, OF, Gardner-Edgerton HS (KS) 5.67 +/- 3.79
5. Taylor Jungmann, RHP, Texas 7.33 +/- 3.21
6. Danny Hultzen, LHP, Virginia 7.67 +/- 3.51
12. Matthew Purke, LHP, TCU 10.67 +/- 7.09
31. Taylor Guerrieri, RHP, North Augusta HS (SC) 34.33 +/- 35.91
Both Matthew Purke and Taylor Guerrieri might fall off this list. Based on reports, it sounds like more and more scouts are growing weary of Purke. This downgrading is apparent in both Law's and Faleris' March rankings, but is not in Baseball America's February rankings. Due to BA reacting to what the field tells them, they will be slightly slower in gauging value and a month old list will affect that even more. I imagine a re-ranking from BA would result in Purke being in the 12-17 range with a much narrowing standard deviation. Guerrieri would probably have the same fate. If BA would re-rank their list, Guerrieri would probably fall within the top 50 and he would like find himself in the 20s with a standard deviation insufficient to make this list.
I should note that players not mentioned on that list would not be reaches. Based on merely standard deviations, it would be safer to use a two standard deviation measure to indicate a "total universe" of considered selections. Even then, it should not be used as a hard and fast rule. Joe Ross (ranked 47th with the composite mean) would qualify for this list while Archie Bradley (ranked 9th) would not. I'm not certain what a more solid rule would entail.