Just my thoughts and reasons are Loyd Waner, the only player out of the set made his debut April 1927, John McInnis & Rogers Peckinpaugh last season 1927, Stanley Coveleski last season 1928. Only one player's last season in 1925 was George Burns. I would think the company would have issued the cards during the summer months starting around late June so they had time to get photos. Also the variation on the backs, differentiating 1927 and 1928