St. Louis also acquired Caleb Ferguson from the Cincinnati Reds for $250,000 in international bonus space.
Nootbaar, 28, is slashing .234/.333/.354 with a career-low three home runs and 16 RBI through 48 games.
Eagen, 23, has a 4.95 ERA with 109 strikeouts in 87.1 innings, giving up 34 walks and 80 hits. Santana, 21, on the other hand, is showing out.
The Dominican pitcher is tossing a 2.14 ERA in the minors (0.57 ERA in Double-A in 11 games) with 70 strikeouts in 46.1 innings.