The previous poster said it better than I could. I grant you there are differences. Even as pinch runners, you might see Plouffe replaced only with Nunez, who can stay in the game to play 3B, and Santana can enter a game in CF if Buxton comes out of a game, which ironically is not likely given the construction of the bench and Molitor's tendency not to use pinch hitters. I would call Nunez third string 3B behind Plouffe and Sano, and Santana as third string CF behind Buxton and Rosario, maybe even behind Mastroianni. We already have backups at those positions. If a middle infielder went on the DL, I would like to see Polanco called up, though I suppose either Nunez or Santana could fill in or trade off for a couple weeks.