I have always liked the Novelty Cutlery postcard set. The 1907 date has always seemed too early to me, so I did a little bit of research which has lead me to believe that the set was issued in 1910 - the same year as the PC796 Sepia postcard set, which has exact same checklist and uses the exact same images.
I am sure that I have made some dating mistakes in my research, so if you can correct any of my findings, please do.
First of all, Sam Frock is included in the set. Between 1907 and 1909, he pitched in a total of 13 games and in 1910 he pitched in 46, starting 29 of them. I doubt that he would have been included in a set until 1910. His uniform is a bit of a mystery, but it may be a Pirates, who he did not play for until 1909.
Frock 2.jpg
Dooin's uniform does not have a patch on his chest. The only year that Philadelphia did not have a patch on its chest was 1909
Dooin 2.jpg
Brown, Chance and Overall are shown in the same uniforms, which date from 1909
Chance 2.jpg
Chase's uniform has an "NY" on the sleeve. The first year that this was used is 1909.
Chase 2.jpg
So, the earliest that these photos could have been taken is 1909 which means that they were probably not produced until 1910.
All of my uniform data was taken from Mark Okkonen's book on baseball uniforms.
I have only been able to find four Novelty Cutlery postcards with postmarks on the back - 1911 (2), 1912 and 1914.
Lastly, this famous image of Cobb and Wagner was taken during the 1909 World Series. There is no way that the Novelty Cutlery company would have produced this set right after the 1909 World Series - they would have waited until at least the beginning of the 1910 season or even as late as the 1910 World Series.