UPDATE - 20 January 2017
A Bernie Williams postcard has surfaced featuring Bernie at the bat, wearing a jersey featuring the "7" on the sleeve, memorializing Mickey Mantle who had died in August 1995. That means the "1993" list is probably a mix of postcards from 1993, 1994 and 1995 (or even 1996 given how the #7 was only used late in the season). Thanks to eagle-eyed Kid4hof03 on FreedomCardboard who pointed this out.
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UPDATE - 31 December 2015
Thanks to Michael over at New York Yankees baseball cards, we now have solid information for splitting these postcards into individual 1992 & 1993 sets. The list below has been updated accordingly.
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UPDATE - 25 June 2015
I'm now thinking this is actually two or three separate sets, or the set was issued continuously over two or three years. This morning on eBay I caught an auction with previously unseen cards of Danny Tartabull in a portrait shot, another Kevin Maas with a different photo and a Roberto Kelly. Kelly wasn't even on my radar for some reason, even though he was an All-Star for the Yankees in 1992, so I don't know why I was surprised. Checking the same seller's completed auctions turned up another lot that included Buck Showalter, Mark Conner and new-to-me cards of Clete Boyer and Yankee Stadium.
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UPDATE - 15 January 2013
I saw the Maas postcard on eBay, so the set is now up to 26. I'm going to start posting images of each postcard as I find them so collectors might have a slightly better chance of recognizing them. I suspect the black & white cards are copies of the originals, but until I find color versions, these are all I have to work with.
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UPDATE - 09 December 2011
A couple more of these showed up on eBay recently, but they are no help in narrowing the set down to a single year as all six individuals were with the team from 1992-93.
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UPDATE - 04 December 2012
A much larger assortment of these has hit eBay, bring the checklist up to 25. I finally have verification of most of the starters of the team.
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The postcard arrived today, all the way from Los Angeles. It was interesting to see that as soon as I got my shipping notice, the seller immediately had a second one posted for sale. Considering he said he was given these as a gift, and he only had the Meulens, Showalter and Howe, he probably has a stack of them from an in-person signing from way back when. I have to revise my date estimate to either 1992 or 1993 as those were the only years Meulens and Howe were on the team together with Showalter at the helm. By 1994, Meulens would be playing in Japan and out of the Yankees system altogether.
Here are the front and back together:
No joy on Googling SPORTSPRINT/ATLANTA aside from more references to that 1994 Greenville Braves set. Ditto for the photographers and what was presumably the outfit that provided the photos.