[RUKen]

Getting back to the photo with seven players, I believe that Buttons Briggs is in the middle of the back row. So we have:

Back row: Del Howard, Buttons Briggs, Doc Casey
Front row: Carl Lundgren, Bob Wicker, Jimmy Slagle, Mordecai Brown

Brown and Briggs joined the team for the 1904 season, and Casey and Briggs were traded away in December, 1905. The inclusion of Howard was puzzling, but then I found this, in the February 6, 1904, edition of Sporting Life (page 4, column 2): Selee has signed a kid named Dell (sic) Howard, from a little Illinois town. Bob Wicker recommended him, and says that for a beginner Howard is a wonder. He is an outfielder, and is touted as the goods. According to Jim Hart, the lad will be given a fair chance, and may make the team as a utility outfielder.

Voila! Frank Selee was the manager of the Cubs in 1904. Howard tried out with the team during spring training that year, but ended up playing in Omaha in 1904 and Pittsburg in 1905.