There may be only 1 ball per game that Gomez gets to that Kotsay falls on his face just short of, but it may come at a huge moment in the game...exactly what happened in game 3. The same can be said on offense, but you have more control over the situation whereas on defense you cant predict that a ball will be hit to CF. Bases loaded, 2 outs, the difference between a flyout and a double could end up leading to 3-4-5 runs against you, but if you really think Kotsay is the better bat and Gomez comes up with the bases loaded and 2 outs you can choose to pinch hit there. Also, wOBA does include SB/CS so that probably gives Gomez a decent boost, endaround said better offensive player, not hitter.