Lack of a reliable closer is only a symptom of the real issue I'm calling to with either of those teams, which is about a refusal to stockpile real depth in bench and bullpen roles. Makeshift closers tend to be at the end of makeshift bullpens, and a makeshift bullpen won't hold in the playoffs. Similarly, platoon roleplayers can have great years over a regular season when their slumps and hot streams average out, but when the level of competition goes up in the playoffs I wouldn't expect them to sustain their surges very long if left exposed in starting roles. Heck, look what happened to Nava this year.
Fortunately, we had stockpiled enough depth and were sufficiently nonstupid that we didn't put the entire postseason on Koji's arm. Which of 3-4 talented arms to use in which role, is the same discussion it would be if we were debating which of 3-4 utterly talentless arms to use in the same role. It's the talent that matters, which reliever used where is mostly a question of rearranging furniture, and any possible gains are minor enough to make the whole argument little more than noise to me.
I'm not a slave to the closer mentality. Most good relievers can probably close at a decent level, but when you have a guy who's getting it done at a level well above decent, that's a good time to leave well enough alone.
I just feel that it's misguided to make the issue about the closer when it's really about picking up quality arms and building the bullpen as a whole, top to bottom, to save leads.