https://theathletic.com/1075513/2019/07/14/marcus-semien-reflects-on-the-trade-that-sent-him-to-oakland-and-andrew-vaughns-future-with-the-white-sox/
He was the #4 prospect for the White Sox (Erik Johnson was somehow first) but never was considered a consensus Top 75 MiLB prospect.
Scouting Grades: Hit: 55 | Power: 45 | Run: 50 | Arm: 50 | Field: 50 | Overall: 50
Semien has been a revelation since signing as a sixth-round pick in 2011. After totaling 10 home runs in three college seasons at California, he has gone deep 35 times in his two full pro seasons. Two of those long balls came during Semien's first big league callup last September.
Semien is more of a tablesetter than a slugger, though, and he led the Minor Leagues with 110 runs in 2013. He controls the strike zone well and repeatedly barrels balls with his compact stroke. Semien enhances his average speed with good instincts on the bases.
Drafted as a shortstop, Semien played a lot of second base last year and mostly third base while with Chicago. He profiles best as a second baseman, offensively and defensively, but he has the savvy to get the job done at shortstop. Semien has nothing left to prove in the Minors and only needs to have the White Sox clear a spot for him in their lineup.
mlb.com
Maybe Davidson had the higher profile because he was always a highly-touted prospect (up to that point), but he had already lost some of his shine from disappointing results with the Diamondbacks, especially the the high strikeout numbers, and he was also older by that point in time. There were also questions about his defense.
Pretty much everything was uncertain except for his flowing locks of hair.