This is a fascinating trade to me.
Neither of these players is a star by any means but they both have some useful talents.
Black, for instance, looks like he could mash the ball as a flyball hitter with great gap and over the fence power. He won't give you much defensively at first base but he will draw some walks and has about average contact abilities and a good head on his shoulders. He turned 27 a day ago and just hasn't been given much of a chance to prove himself in Milwaukee. It certainly didn't help that his path was blocked by 3-time All-Star and 1971 SJL Rookie of the Year, Josh Schultz, who is 2 years his junior. The Boston Berserkers, his new team, had a big need at first so hopefully this will finally mean Black gets a chance to prove his value as a starter.
Then there is Nate Harper, who at nearly 26 years old is considered a plus fielder with top of the line speed and base-stealing/base-running abilities. Harper doesn't profile as a great hitter, but he is solidly average or slightly above average all around at the plate and with his speed and defensive skills he could certainly provide a team value at the least in a platoon role if not as a starter. Although there are some questions about Harper's baseball smarts, he is considered a hard-worker and a very likable teammate. Although he produced 1.4 WAR in 100 games- only 27 in a starting role- in 1972, he remained a peripheral member of the Berserkers team. The Milwaukee Cadets have a deep stable of outfielders on their active roster but really none that profile much above league average so Harper has a chance to make an impact on his new team.