Sorry, I completely blanked on the dimensions you gave. I had something smaller in my mind, but if yours are 3-1/2"x5-1/2", they are exactly as Todd and David said. The Tobin in particular is definitely a George Burke photo, most likely printed from the original negative, but at a much later period than when it was taken. As David said, Jim Rowe had a great many of George Burke's negatives that he obtained from Burke's assistant/apprentice George Brace, who took on Burke's photo archives when his health was failing in the late 1940's. Both Rowe and Brace produced copius prints from Burke's negatives. From the 50's to I'm guessing the late 70's or early 80's, they had the same standard Kodak real photo postcard back, with more recent ones having the blank back like your Tobin due to the Kodak back stock being more difficult to obtain (per Mary, Brace's daughter). Based on that, I would say the blank-backed Tobin is a "real photo postcard" (minus the printed postcard markings) produced somewhere from the 1980's on. I don't recognize the handwriting as Rowe's, Brace's, or Mary's, though I belive Mary at least has had help from other family members in recent years (she just recently sold or transferred the archives to John Rogers' outfit, judging by the change in contact info on the bracephoto website and large number of Burke negatives popping up in Rogers' usual outlets in the last few months).
Edited to add: Good luck in putting together a "set" of Rowe or Brace postcards, as either would number into the many thousands. Team sets from a given year would be much more realistic, and that is how many collectors bought them. Both men used images from other sources as well, particularly for earlier (pre-1930's) photos, and quality varies widely on those. Brace developed some skill under Burke as a photographer, and continued to take his own photos up into the late 1980's, whereas Rowe appears to have been more of an amateur, which often shows in the quality of his prints.
A few other Tobin photos by Burke for your amusement:
1931-39 Pittsburgh Pirates (3-1/2"x5-1/2")
1940 Boston Bees (4"x6")
1941-45 Boston Braves (3-1/2"x5-1/2")
