In addition to the team photos I mentioned earlier, which were available from shaving cream dealers, the Examiner did indeed offer the 200 Mendelsohn card set known as m101-5, for a three-month subscription. This is found on p. 15 of the Wednesday 4/5/16 edition--there is likely a similar ad two days later in the edition touting the National League players.
http://digital.chipublib.org/cdm4/cl...CALE=0&DMTEXT=
Curiously, the ad lists a few of the players included in the set and names Matty--who is of course not in the set at all. It also references "Joke" Tinker.
Finally and even more curiously, when the paper lists all AL players and their last year's records in the Wednesday edition, it includes the scarce Cady and omits Mordecai Brown, and Cady's pic is among those shown. Also, in the NL paper two days later, Beals Becker is listed and his pic shown. Thus two of the scarce variations were perhaps meant to be included, but not the third--Bobby Wallace. Either there were multiple printings of the m101-5 sheet to explain why yours does not have the variations, or maybe there had been some prototypes sent by Mendelsohn used for the ad but not used at the time of distribution.
Oops, I just saw Bobby Wallace's photo in the Examiner newspaper ad as well, although he and his 1915 stats are not listed.