In 2016, Orioles leadoff hitters had a combined wRC+ of 94. That was fourth worst in the American League. O's hitters in the second lineup slot, meanwhile, had a wRC+ of 121. That was good enough for third best.
The majority of leadoff plate appearances went to Adam Jones (488) and Joey Rickard (183). Jones is not a leadoff hitter, but did a competent job there last season (108 wRC+) while not reaching base at a high clip (.320 OBP). Most of the plate appearances in the No. 2 lineup spot went to Hyun Soo Kim (259), Manny Machado (164), and Jonathan Schoop (125). Machado and Kim were two of the O's best hitters last season, so it's not surprising then that the results from that spot in the order would be better than those of the leadoff spot.
It's well-worn territory by now where certain types of hitters should go in a team's lineup (and also that, by and large, the lineup order isn't that important - but it still matters somewhat and is easy/fun to discuss). There's plenty to read on efficient lineup ordering, and I summarized the Orioles' situation last season while arguing that Machado should bat second, not third. Machado should certainly bat second the majority of the time in 2017, while Jones should be placed lower in the order.
The first part of who should bat leadoff, then, is at least clear. Kim should bat first against right-handed pitching. In his first major league season, Kim was nearly 30% better than league average against opposite-handed throwers. Of all batters with at least 300 plate appearances, his .382 on-base percentage was 18th best in the majors. Against right-handers only, his .393 OBP was tied for ninth best overall (minimum 250 plate appearances).
For the Orioles, it's been a while since they had someone with Kim's on-base skills. In the Expansion Era, the longest the Orioles had gone from 1961 to 2008 without a hitter with an on-base percentage of at least .380 was three years. The Orioles went eight years, however, between Markakis's .406 OBP in 2008 and Kim's .382 OBP last season. The Orioles need to do whatever it takes to utilize Kim's skills at reaching base while they have him.
There's a decent argument that Kim should play every game and bat first, despite his struggles in limited duty against left-handed pitchers. I'd have no issue with that. Another option, though, would be to deploy a leadoff platoon: Kim vs. right-handers and Rickard vs. left-handers. I'm far from the only person to believe that platoon would make sense, even if you don't think that Kim (129 wRC+ in 323 PA) and Rickard (131 wRC+ in 90 PA) will be able to replicate their strong showing against opposite-handed throwers going forward.
But, so what? What are the alternatives? It's not Jones and his career 107 wRC+. Seth Smith is similar to Kim as a more proven left-handed platoon bat, so he might work. Kim on-base skills seem superior, however, so Smith could be a nice fit in the middle of the lineup, since Buck Showalter relishes alternating right- and left-handed batters (or at least trying to).
There's no option that sounds more enticing than either batting Kim leadoff full-time (less likely) or using the Kim/Rickard platoon (more likely). Showalter already learned his lesson last season when he benched Kim for most of April. It's time to give him a shot from day one in 2017 and see what he can do.
Stats via FanGraphs, Baseball-Reference, and the Play Index