I am a day late with these guys but they made their major league debuts as Minnesota Twins on July 2.
Jarvis Brown (OF) – July 2, 1991 – Drafted by the Minnesota Twins in the 1st round (9th pick) of the 1986 amateur draft (January). Player signed May 23, 1986. ) for 2 in his debut at the Skydome in a 4-3 loss to the Blue Jays.
Gary Serum (P) – July 2, 1977 – Signed by the Minnesota Twins as an amateur free agent in June 1975. Debuted as a reliever at Met Stadium in a 6-2 loss to the Angels pitching 2 innings and striking out 2 while giving up just one hit and no runs.