All three players have a Philadelphia connection. Jim Konstanty pitched for the Phils for seven seasons and would have been referred to as a relief specialist back in the day:
Not a Philllies player but definitely a Philly native, The Pest:
All three backs are blank:
In any event, these were clearly never released to the public and their yanking, no doubt due to contractual wranglings with Bowman, likely killed off the larger, over-arching Baseball Candy issue the MLAS (and Connie Mack All Stars) were a part of, just like Red and Blue Backs and the Team cards. In fact, the MLAS standups only came with Blue Backs in a five cent configuration. All of the MLAS cards are difficult but these three are impossible. Personally, I don't consider them part of the set.
As you can see from the link above, prodigious pricing prevailed!