George Smith spent time in the majors with the Tigers and Red Sox, and was a starting second baseman for a while for both teams. His major league career ended in 1966, but he kept playing in the minors.
Without explanation, he starts up 1967 in the Giants' system, at Phoenix. Why? I found this exerpt from the book The Curse of the Bambino or How the Sox Finally End It by LIAM...
"Friday, July 21, 1967... ...Norm Siebern, who came to the Red Sox in exchange for infielder George Smith, played for the first time..."
This isn't listed for Smith at all, and Siebern's Baseball Reference page has the transaction as the following:
"July 15, 1967: Purchased by the Boston Red Sox from the San Francisco Giants."
Well, we now know what (who!) the purchase price was.
A biography of Siebern by SABR
"his brief National League tenure ended on July 16, when he was acquired
by the Red Sox for the waiver price of $20,000. In order to claim
Siebern on waivers, Boston also optioned injured outfielder George Smith
to the Giants farm club at Phoenix."
Looks like a trade to me.
Smith went to the Senators and Astros systems in 1968, we will see if we can come up with the hows and whys on those...