Understanding Roger Bernadina’s KBO Rebirth

A lot of things have clicked for the Kia Tigers this season, chief among them being their offense’s record production. Kia’s fearsome lineup features three of the Korean Baseball Organization’s top-10 hitters by batting average, and five of the top-20 hitters by wRC+, and is a driving force behind the team’s domination of the standings, currently sitting in a comfortable 1^st place at 64-34-1, five games up on the second-place NC Dinos.

A major force behind the dominance of the Kia offense has been the unexpected emergence of their new center fielder Roger Bernadina, in his first season in the KBO. Just a season ago, Bernadina was toiling in the minor leagues, playing with the Las Vegas 51s, the New York Mets’ Triple-A affiliate.

The difference between the old Bernadina, a failed prospect who played seven partial seasons in Major League Baseball, mostly with the Washington Nationals, and the current Bernadina, who hits leadoff for the Kia Tigers’ offensive juggernaut, is stark.

Roger Bernadina career stats, 2008-2017
league	years	G	AVG	OBP	SLG	wRC+	WAR
MLB	2008-14	548	0.236	0.307	0.354	81	1.2
KBO	2017	95	0.320	0.383	0.551	135	3.9

In less than a fifth of the games played, Bernadina has already accumulated over three times his MLB WAR and hit over half as many home runs (19 to 28). By wRC+ he has been the 16^th most productive player in the KBO this season, and by WAR, he has been the 6^th best position player in the league. On Thursday night he hit for the cycle, becoming only the third foreign player to do so in the KBO. Quite a jump for someone who was a career 81 wRC+ hitter in the MLB.

Which of course begs the question: What’s changed? In less than a season, how has Roger Bernadina improved this much?

It isn’t plate discipline; Bernadina is actually walking slightly less (7.7 percent in the KBO versus 8.2 percent in the MLB) and swinging more (50.3 percent vs 42.1 percent). His strikeouts are down from 21.3 percent in the MLB to 17.4 percent in the KBO, but that change may be more a function of the leagues themselves (the MLB’s higher overall K% means Bernadina’s mark is about league average in both leagues) than any adjustment Bernadina himself has made.

Bernadina also still profiles as the same type of hitter, hitting a majority of his batted balls on the ground, with a moderate preference to pull. He never displayed particularly drastic platoon splits, hitting roughly the same against lefties and righties, and this tendency is also unchanged. Though his batted-ball characteristics would have made him a reasonable shift candidate, shifts were almost never employed against him in the MLB, so his increased numbers in the KBO are also not the result of the KBO’s relative lack of defensive shifts.

The biggest difference is the change in Bernadina’s batting average on balls in play. His current KBO BABIP is .353, a drastic increase from his career MLB BABIP of .288.

On one hand, Bernadina profiles as the type of hitter than might naturally run a higher BABIP. He runs well, having rated as a positive baserunner and base-stealer in both his time in the MLB (59 steals, 83% success rate, 8.9 BsR) and the KBO (21 steals, 81% success), and the fact that he is primarily a ground-ball hitter should give him ample opportunity to take infield hits and run a higher BABIP.

However, his track record shows this to not be the case. BABIP is a statistic that takes a long time to stabilize, and as such his career average is more indicative of him as a player than his current 2017 outlier mark. With no other changes in batted-ball profile or batting approach, Bernadina’s increased BABIP, and by extension increased offensive production, is more likely the result of fortunate circumstances and luck than any real change in skill.

That being said, simply acknowledging that Bernadina has been lucky this season does not diminish his performance. Regardless of whether he is performing to his expected outcomes or not, he has been a productive member at the top of the Kia Tigers’ lineup and, perhaps even more interestingly, has hit better as the season has progressed.