The Los Angeles Dodgers have been a subpar offensive team since the calendar turned to May, no matter how you slice it. They're a below-average team according to FanGraphs' offensive component of Wins Above Replacement . They're 4-5 this month in the standings, having outscored opponents 36-33. It's a small margin, and hardly reason to panic, but it goes a long way toward explaining why Hyeseong Kim — not Alex Freeland — is keeping his roster spot when Mookie Betts gets activated from the injured list ahead of the Dodgers' series against the San Francisco Giants. Kim is slashing .289/.353/.395, Freeland .235/.309/.337. Both players can handle the two middle infield positions. Both bat left-handed (Freeland is a switch-hitter, but the Dodgers much prefer him as a lefty). Both made their big-league debuts last year, when Freeland was 23 and Kim 26. But in the last year, Kim has taken a meaningful step forward at the plate, a change that goes beyond his slash line.…