Lou Lombardo pitched for the Giants for just that one season as a 19-year-old. He started in the business as a 15-year-old! After a couple ineffective appearances, that was it for Lou in the majors and he was shipped back to the minors, and then to the Tigers' system in 1949. This isn't documented on his Baseball-Reference page, but I found the deal here, in the Toledo Blade of May 7, 1949:
“Mud Hens General Manager Bob Evans’ plans to bolster his club’s wobbly mound staff received another shot in the arm today as he announced the purchase of Lou Lombardo, 21-year-old southpaw, from the Minneapolis Millers.”
Lombardo finished his career in lower minors after that season, out of baseball at age 25.
Ken Trinkle was a pretty good relief specialist who led the NL in appearances in 1946 and 1947 with an ERA under 4. He was dealt to the Phillies in 1949, and was sent to their minors in 1950 and 1951.
In 1952, he goes from the Phillies' Baltimore team to Louisville in the Red Sox organization, with no deal mentioned on his Baseball-Reference page. We uncovered this from the Milwaukee Journal of June 26, 1952:
“Gordie Mueller, one of the leading relief pitchers of the American association two years ago, has been traded by Louisville to Baltimore for pitcher Ken Trinkle, 32 year old right hander, formerly with the New York Giants.”
Both Trinkle and Mueller (who played for the Red Sox in 1950) ended their careers in 1952.
Pete Milne, an outfielder, served a few years in the Cleveland low minors before going to the Giants, spending parts of three seasons in the majors.
In AAA he was a very good hitter; and the Giants sent him to independent Oakland in the PCL for the 1952 season in a trade not mentioned on his Baseball-Reference page.
I found the deal here, in the Kansas City Times of Dec. 5, 1951:
“The Oakland baseball club announced today the outright purchase of William (Pete) Milne, left-handed hitting and throwing outfielder, from Minneapolis of the American Association. The price was not disclosed.”
Milne played very well for the Oaks for three seasons before going to Sacramento for 1955 in a deal described here in the Lodi News-Sentinel of March 29, 1955:
“Joe Brovia, one of O’Doul’s favorite ballplayers, will be in right field instead of Pete Milne. The latter went to Sacramento in a straight swap for long-faced Joe.”
That article was a preview of the Oaks' 1955 season. After a poor 1955, Milne played one more year in AA Mobile before calling it a career.
"Ox" Brovia, a big homerun hitter in the PCL. would get one short trip to the majors with the Reds in 1955.
Lombardo from www.attheplate.com
Trinkle from www.baseball-birthdays.com
Mueller from www.pinterest.com
Milne from www.amazon.com
Brovia stolen from richardleutzinger.com