2B Richie Palacios
I'm cheating again. Palacios reached the majors last season with Cleveland, however, he played a minimal role and still has not debuted for the Cardinals. He was traded over the offseason for cash considerations. Among infielders, Palacios has the best chance of reaching the majors of anyone not named Masyn Winn. Palacios is 26 and currently ranks outside the top 30 on most organizational prospect lists.
He's had a strong year, though he's generally demonstrated competence at the plate, evidenced by his career .845 OPS. Palacios won't hit for a lot of power, he has just 25 career homers, but he has solid on-base skills and an advanced approach at the plate. Palacios could play in the majors immediately if called upon.
Most importantly, Palacios is part of the 40-man roster. The Cardinals likely view Palacios as a depth piece, but have demonstrated an unwillingness to let similar players leave for nothing. Thus, he stands at least some chance of holding onto his roster spot over the offseason. In the near term, however, he is likely to be called upon. With DeJong out the door, Donovan shut down, and Gorman questionable due to back pain, Palacios could play in St. Louis as soon as this week, especially if the Cardinals are cautious with Winn.
Palacios' biggest competition for playing time will come from Taylor Motter, who has drawn several starts with the big league squad over the last week. Motter's advantage is his positional flexibility, but his poor offensive performance may encourage the Cardinals to give Palacios a chance.