Spencer hit over 100 home runs in a military-service interrupted MLB career, including the first major league home run on the West Coast, for the Giants in 1958. That he hit it in Seals Stadium, home to the team that, a decade prior, had helped usher in a new era in Japanese Professional Baseball with a triumphant tour that spurned on the two league system, proved somewhat prescient.
After being released from the Reds in 1963, he received several offers from NPB, including one from the Hawks. He settled with the Braves, and quickly regretted not taking up the Hawks offer after witnessing the close fences at their home park. Though he may have challenged Sadaharu Oh for some home run crowns with the Hawks, he still hit 36 to come in second in the Pacific League in 1964, 5 behind legendary slugger Katsuya Nomura.
The team invited him back as a coach in 1971, and, though he showed up overweight with no intention of playing, his coaching duties quickly improved his physique to the point where the team asked him to become a player-coach. The Braves would go on to another back-to-back pennant run with player-coach Spencer , though they could never clinch a Series victory against the powerful Yomiuri Giants.