Left-hander Jackson Kent, Washington's No. It's unclear exactly when the Nationals will confirm this promotion, but the 23-year-old is reportedly set to make his MLB debut this week. When could Jackson Kent make his MLB debut? Wilmington starter Jackson Kent throws during a rough outing for the Blue Rocks in a 13-6 loss to Hudson Valley on July 29, 2025, at Frawley Stadium. So, Kent could make his MLB debut against the New York Mets this weekend if he's officially promoted.