Despite the descriptions of the card as it recently appeared in several major auctions, it is more than just "low population" that causes the excessive demand for the 1914 Cracker Jack Del Pratt. While that certainly is the case, there are other cards in the set with lower populations, that routinely sell for less than the Pratt.
The notoriety behind the Pratt is largely due to being one of just two cards where the player's pose was changed between the 1914 and 1915 issues (the other being Christy Mathewson, arguably the issue's most important card). Collectors who recognize the rarity of the 1914 issue and the difficulty (and expense) of completing a set will often attempt a mixed-year set, substituting the more plentiful 1915 issue when the cards share the same image. When it comes to the Mathewson and Pratt, however, collectors often choose to have both poses in their set. That, coupled with the inherent rarity of the Pratt card, is what causes the demand. In the instance of a similarly scarce card - Beals Becker, for example - a collector can acquire the same pose by tracking down the far more plentiful 1915 Cracker Jack example. But in the case of Pratt, a collector who desires this pose can only choose the 1914 issue. This is the 8th time we have handled a Pratt, and despite the grade, it is one of the finest - the GD grade largely due to a tiny tear in the right edge that is visible in the border of the card, but does not make it into the red background. Some additional areas of staining are evident on the reverse, at each corner, the likely result of scrapbook mounting. Regardless, an exceptionally rare and important card.