I do recall Dom Controneo suggesting the idea--maybe on the SEP 27 post-game show--that having Yelich hit in the leadoff spot may been an experiment to see if the #9 hitters, Joey Ortiz in particular, would get better pitches to hit when the lineup circles around. I would chalk that up to tinkering with an idea during the last week of the season, where games weren't so critical to win.
Frelick at leadoff, with Yelich and Turang in either the 3rd or 5th spot of the lineup seems to make more sense in the playoffs where every game matters.