The Arizona Diamondbacks don't know when you should retaliate.  Sure Paul Goldschmidt was hit with a pitch and will likely be done for the season after suffering a broken bone in his hand.  But anyone who saw the pitch that hit Goldschmidt can tell it was inadvertent and required no retaliation.

Everyone that is except for Randall Delgado and the Arizona Diamondbacks.  Delgado exacted his revenge on Andrew McCutchen in the 9th inning of a 5-1 loss.  McCutchen and the Pirates are in an intense playoff push a game and a half back in the NL Central and now McCutchen is expected to go on the DL.

There are times when retaliation, like it or not, is appropriate but this is not one of those times and this action is indefensible.