Joe Phillips brought up a point about when the term "Personal Model" was first used on a retail glove and what the term implied for the manufacturer. Just considering Rawlings, It seems like the "Catalog Source Book" lists 1953 as the first "Personal Model" in their line of gloves, with the Stan Musial endorsement. I don't have access to a 1953 Rawlings catalog to read what is said about the model but I wonder if Rawlings could have initiated the "personal model" as a tribute to their hometown star, St. Louis Cardinal, Stan Musial.
Many star player, such as Mickey Mantle were seen in ads as "Using and endorsing" a particular "Personal Model" model. I guess at that point they played with that glove. They probably signed an endorsement contract with the manufacturer. It must have really helped retail sales of that glove. My favorite player, Sandy Koufax, wouldn't sign a contract with any of the big four manufacturers. Maybe he didn't like the hype.