The annual ranking of baseball's Top 100 Prospects is assembled by MLBPipeline.com Draft and prospect experts Jonathan Mayo, Jim Callis and Mike Rosenbaum, who compile input from industry sources, including scouts and scouting directors.
• MLB Pipeline's 2016 Top 100 Prospects list
It is based on analysis of players' skill sets, upsides, proximity to the Majors and potential immediate impact to their teams. Only players with rookie status entering the 2016 season are eligible for the list. The rankings follow the guidelines laid out by the Collective Bargaining Agreement, in terms of who falls under the international pool money rules: Players who were at least 23 years old when they signed and played in leagues deemed to be professional (Japan, Korea, Taiwan, Cuba) are not eligible.
Jackson's drop from last year is understandable given that he hit just a combined .207 with eight home runs and 38 RBIs in 76 games while splitting last season between Class A Clinton and Class A Short Season Everett. But the Mariners still expect big things from a youngster who was the sixth overall player selected in the first round of the 2014 Draft out of Rancho Bernardo High School in San Diego.
The Mariners pushed Jackson to start last year at full-season Clinton, but he put up just a .157/.240/.213 line in 28 games before faring better in Everett, where he hit .239/.365/.466 in 48 games.
"With Alex, there's a couple things," Mariners assistant general manager Jeff Kingston said. "Being a kid that grew up in Southern California and was used to nice weather, going to Clinton [Iowa] in April and having to hit in 35- to 40-degree weather is a tough adjustment. And the culture, he had a lot of polished college kids around him and that was a little culture shock for him. I think the game just sped up on him.
"We wanted to get him back to Arizona, get him fully healthy, reset him emotionally, mentally and physically and then send him to Everett in a more conducive environment to have success and just be himself."
Kingston said it remains to be seen where Jackson starts out this season, but that he won't be rushed. Jackson played catcher in high school, but began his conversion to the outfield as soon as he was drafted by the Mariners and hit .280 in 24 games in the Rookie-level Arizona League that year.
"He's still one of our better prospects in the system," Kingston said. "He has as much upside as anybody. As [GM] Jerry [Dipoto] says, we're going to do what's best for each individual player going forward. Just because he finished the year in Everett last year doesn't mean he has to go to Clinton this year. He may go back to Everett. The player is going to dictate the timetable. We're cognizant of the fact he's one of our more highly rated and higher-profile prospects, but we're going to do what's right for him and wherever we think he's at developmentally."