There are 13 teams in the softball league, so there are 13 options for the first-place team. Once the first-place team is determined, there are 12 remaining teams for the second-place spot. Finally, there are 11 remaining teams for the third-place spot. Therefore, the number of different end-of-the-season rankings of first, second, and third place is possible is:
13 x 12 x 11 = 1,716
So there are 1,716 possible rankings.