I feel like the word "luck" sort of throws these conversations off track, because it implicitly removes any sense of responsibility for the outcome of a game. People hear "luck" and they think you're saying that no player or coach can be criticized for what happened in a a playoff game, and that's just not the case.
"Luck," in this case, is really just a one-word stand-in for the idea that small sample sizes are a bitch in baseball, and that a postseason series is the ultimate in high-stakes small sample sizes. Was it "luck" that the Cardinals beat us in the wild card game? Was it luck that the Dodgers took three of four from us in 2013? Not really- those teams out-played us in those games. That wasn't lucky or unlucky, it was just how the teams played in those series (using the word "series" loosely in the 2012 context).
The conflict is whether or not those results really have any significance beyond the games in which they occurred. I, and a lot of other people, basically think that four games (and certainly one game) tell us nothing about the strength of the teams involved. We've out-scored the Marlins 14-3 in two games this season. We're probably going to be worse than them once the entire season is played. We took the season series from the Nationals last year, and we finished approximately 723 games behind them in the standings.
It's not at all unlikely for a noticeably worse team to win one game, as the Cardinals did in 2012. And it's barely more unlikely for a worse team to win three of four, as the Dodgers did in 2013. I mean, we see things like this in the regular season all the time, don't we? Inferior teams wins a series in June, no one blinks an eye. It happens in October, and all of a sudden that says something deep and significant about the teams involved.