I haven't done a deep dive on it but looking at some numbers quickly... Montero tends to walk left handed hitters a lot more than righties so they wanted Neris to face Mullins in the 8th. Neris also has a much better K/BB ratio against lefties than Montero. Santander is a better hitter from the right side so as long as he is hitting lefty you feel ok with that matchup whether it is Neris or Montero. Stanek walks too many guys to be a closer. He has 6 more walks than Montero in 10 less innings. Also, Stanek is arb eligible. Giving a reliever a bunch of save opportunites is one of the best ways to jack up his arb numbers.