The Nationals traded Diaz to the Orioles on Wednesday in exchange for Kyle Nicolas.
Diaz has spent the entire season at High-A Wilmington, slashing .253/.360/.406 with five homers, 31 RBI, 28 runs and 13 steals through 200 plate appearances. The 23-year-old infielder will likely remain at High-A to begin his tenure with the O's, but he could make a push to reach Double-A Chesapeake by the end of the season.