Etymological Note: Baseball spring training is held in warm southern states, so to join the team as a regular player is almost always to literally go north to the team’s home city.
Citations:
[1903Decatur Review (Illinois) (June 2) p. 3: Pitcher Eul, the Peoria man who has been dickering with McFarland, got in in time to go north with the team and John Mertens was left at home.] 1942Syracuse Herald-Journal (N.Y.) (Apr. 6) “Skidding the Sport Field with ‘Skid’” p. 14: Vance will probably go North with the club and if he does it means that infield practice will be well worth watching because his rifle-like arm is the big feature of Syracuse warmups. 1952 Jack Hand Joplin Globe (Mo.) (Mar. 21) “BoSox Will Go WIth Oldsters As Long as They Keep in Race” p. 7B: Eight survivors of the six-week training school at Sarasota are due to go north with the club. 1983New York Times (Feb. 28) “Strawberry Draws Attention” (in St. Petersburg, Fla.) p. C6: “He’s such a good young player,” Manager George Bamberger said, “that there’s absolutely no point in rushing him. In my mind, I don’t think he’ll go north with the club. But we expect him to make it before long, and to stay a long time.” 1987 Dave Perkins @ Dunedin, Fla. Toronto Star (Can.) (Feb. 25) “Caudill’s forkball a ‘slice’” p. C1: Despite his luscious contract—Caudill made $1,233,000 for his lost season in 1986 and is signed for three more years—he needs to beat people out to go north with the team. 2004 Allen Ariza NYFansOnly.com (Nov.21) “CD’s Phuture Phillie Phenoms…North Philly 40”: A player told that he has made the team is referred to as “going north with the club.”