Krook signed a minor-league contract with the Athletics on Friday.
Krook surrendered two earned runs in one inning during his lone MLB appearance with Baltimore last season. He was much more effective during his time with Triple-A Norfolk, however, posting a 3.92 ERA and 1.41 WHIP across 43.2 frames. Now with the A's, the 30-year-old southpaw will most likely fill in as organizational depth at Triple-A Las Vegas.