The numbering is based on the uniform numbers of the Blue Jays. Other Frie Safety sets have uniform numbers as well, which is why the cards are still NNO.

Although this is a 36-card set (card 36 is an NNO checklist card), the numbering is not the traditional 1-36 format.
There is a card #1 which is Eddie Zosky, but the last numbered card is # 66 Juan Guzman.

The numbers not used in this set are:

6,13,15,17,20,21,23,26,32,35,36,37,38,44,45,49 and cards 51 through 65

Card numbers that have been used that are greater than 36 are: 39,40,41,42,43,46,47,48,50 and the aforementioned 66 card.