The Kia Tigers Are Doing Everything Right — Except on the Weekends

The Kia Tigers are doing a lot of things right. At 64-34-1, they are in first place in the Korean Baseball Organization, with a comfortable five-game lead over the second-place NC Dinos. As a team, they are slashing a cumulative .306 / .375 / .479, and are first or second among teams in the KBO in virtually every offensive category.

category	H	2B	3B	HR	R	K	BB	AVG	OBP	SLG	wRC+
2017 Kia	1092	213	24	120	658	620	356	0.306	0.375	0.479	116.9
league rank	1	1	2	3	1	1	2	1	1	1	2

But the emphasis on offensive firepower has not come at the expense of pitching; while Kia’s hurlers are not dominating the league the way their hitters are, their pitching staff ranks first in the KBO in WAR (15.8), and has above-average marks in ERA+ (105) and FIP+ (105.6). This is a solid, well-rounded team.

However, Kia has had one major flaw throughout the season: They play significantly worse on the weekends.

The KBO schedule is set up such that each team plays two three-game series per week, one from Tuesday to Thursday, and one from Friday to Sunday. Throughout the 2017 season, Kia players, both pitchers and batters, have performed significantly worse on the weekends. The effect is most noticeable on the hitting side, with a precipitous drop in performance in games that happen in the second, Friday to Sunday, series of the week.

The table below shows the batting splits for the top-10 Kia hitters (by plate appearances), as well as the team as a whole, and clearly shows the distinction between the mid-week and weekend series. From Tuesday to Thursday, Kia hits like, well, Kia. But from Friday to Sunday, Kia’s cumulative batting line is comparable to that of the Lotte Giants and Samsung Lions, who are in seventh and eighth place, respectively.

Kia Tigers 2017 time of week batting splits, descending by △OPS
pos	hitter	weekday		weekend		difference
		AVG	OPS	AVG	OPS	△AVG	△OPS
LF	Choi Hyoung-woo	0.440	1.373	0.290	0.883	-0.150	-0.490
SS	Kim Seon-bin	0.475	1.135	0.284	0.701	-0.191	-0.434
1B	Kim Ju-chan	0.361	0.986	0.192	0.555	-0.169	-0.431
3B	Lee Beom-ho	0.308	0.979	0.250	0.781	-0.058	-0.198
CF	Roger Bernadina	0.341	1.004	0.301	0.865	-0.040	-0.139
2B	An Chi-hong	0.333	0.953	0.317	0.822	-0.016	-0.131
DH	Na Ji-hwan	0.327	0.925	0.284	0.954	-0.043	0.029
1B	Seo Dong-wook	0.286	0.778	0.311	0.863	0.025	0.085
RF	Lee Myeong-gi	0.303	0.797	0.370	0.884	0.067	0.087
team	Kia Tigers	0.335	0.935	0.273	0.768	-0.062	-0.167

This stark difference in team performance has borne out in the team’s record. On Tuesday to Thursday games, Kia is 41-9, an .820 winning percentage, or an 118-game-winning pace over a full 144-game season. For comparison, the KBO single-season wins record is 93, set by the 2016 Doosan Bears, and the 90-win mark has only been eclipsed one other time, when the now-defunct Hyundai Unicorns won 91 in 2000.

However, on Friday to Sunday games, Kia is 23-25-1, a .469 winning percentage, or a 68-game-winning pace. If Kia had a .469 winning percentage this season, they would slot in at eighth in the standings between, guess who, Lotte and Samsung.

There are no clear reasons for this drop-off. Kia’s schedule has been fairly balanced between the weekday and weekend series, and they have faced good and bad teams alike. Other teams have some variation between weekday and weekend, but there is no league-wide trend toward weaker weekends, and especially no performance gaps as severe as Kia’s.

However, as Kia is still well in control of the 2017 KBO standings, and performing well overall, this weekend drop-off stands as more of a curiosity than an actual problem. Perhaps it actually makes the team even scarier; despite running roughshod over the rest of the league, the Kia Tigers still have room to improve.