Dean has by far the most MLB experience of the group, appearing in 98 games with the Marlins over the past two seasons. St. Louis acquired Dean in January, though Dean faced a lot of competition for an Opening Day roster spot, given the amount of outfield depth in the Cards’ camp. Dean played mostly as a left fielder in Miami with a few appearances in right field and first base, and he hit .223/.268/.388 with 10 homers over 311 plate appearances.
Williams faced a similar situation as Dean did in facing an uphill battle to win an outfield job, though Williams’ left-handed bat makes him a solid call-up possibility during the season given that Cardinals’ other outfielders are mostly right-handed hitters. A second-round pick for the Diamondbacks in the 2013 draft, Williams was dealt to the Rays in 2014 and then came to St. Louis as part of the return in the Tommy Pham trade package at the July 2018 deadline. Shortly before that deal, Williams received his lone bit of MLB experience to date — a single plate appearance on July 21, 2018.
As noted by Derrick Goold of the St. Louis Post-Dispatch, Sosa is eligible to be sent down due to a fourth option year, as opposed to the usual three. After the Cardinals cut ties with Yairo Munoz, Sosa stood to benefit from that unusual situation, and he played well in Spring Training in his bid for a utility infield job. While at Triple-A, Sosa will be the “de facto backup” to Cardinals’ starting shortstop Paul DeJong on the big league roster, should DeJong suffer a longer-term injury. Sosa has had only a few more cups of coffee in the big leagues than Williams, as Sosa has appeared a total of 11 games for St. Louis over the last two seasons.