The various E91 issues are often overlooked among hobbyists, as the illustrative images have long been considered "generic" illustrations like the N284 Buchner "Gold Coin" cards, none intended to resemble its actual subject.  However, extraordinary research conducted by collector Brian Parker have convinced this writer that many of the images in this set are derived from actual player photos including roughly two-thirds of the E91-A set - and Christy Mathewson.

Of course generic or not, the card of Christy Mathewson (misspelled "Matthewson") is one of the issue's key cards, and is deceptively scarce.  This example has been graded VG 3 by PSA, with evenly-rounded corners, some mild surface wear, but strong color and centering that strengthen it's visual appeal.  

*we highly recommend reviewing Brian's E91 article, posted on the Net54 message board at https://www.net54baseball.com/showthread.php?t=116102&highlight=e91