Patrick is right on in declaring the B18 blanket does not depict catcher Billy Kelly. Though Kelly did play for the Pirates through 1913, he doesn't resemble the B18 image, which clearly shows the player wearing something other than a catcher's mitt.
However, the Baseball Reference image of Joseph H. Kelly (see below) looks very much like the B18 likeness and since he was the Pirates' regular center fielder in 1914, it seems more likely that is whom they intended to portray.
Unless we find a photograph of Hall of Famer Joseph J. Kelley that matches this image, it seems a bit of a reach to connect this blanket to the HOFer, especially since he last played in the majors in 1908, last played in the minors in 1910 and only appeared for Pittsburgh briefly in 1892.
https://www.baseball-reference.com/p...ellyjo03.shtml