A baseball season is long enough to contain two completely different players inside the same body, and in 2026, San Francisco Giants outfielder Lee Jung-hoo has become a case study in exactly that. Through the season’s first half, he was hitting .302, a number that placed him among the National League’s more productive outfielders and validated the optimism that followed his rookie year. In the second half, that number fell to .230. In September, it has fallen further still — all the way to .140, on 6 hits in 43 at-bats. His overall season average, which briefly touched territory near .300, now sits at .276 and sliding.
The timing crystallized on September 14, Korea time, when Lee went 0-for-5 in a home loss to the San Diego Padres at Oracle Park, a game that also completed a three-game sweep at the hands of the Padres. It was a quiet, uneventful box-score line in isolation — the kind of game that, on its own, would barely register as news. Stacked on top of five months of accumulating data, though, it became the latest data point in one of the more startling reversals of form in this MLB season: a player who spent 2025, his rookie year, doing the opposite of this — starting cold and finishing hot — is now doing the opposite of that opposite.
For readers newer to his story, Lee Jung-hoo did not arrive in San Francisco as an unproven prospect. He spent seven seasons with the Kiwoom Heroes in the Korea Baseball Organization, establishing himself as one of the most consistent contact hitters in the league before signing with the Giants ahead of the 2025 season. His KBO résumé — built on plate discipline and an ability to spray hits to all fields rather than raw power — is part of why his rookie-year adjustment period, and now this second-year reversal, has drawn such close attention from Korean baseball media. He was not supposed to be a hitter prone to prolonged cold stretches; contact ability of the kind he showed for years in Korea is usually the exact skill set expected to hold up best against a full MLB season’s workload.
The Numbers, Laid Out in Order
Strip away the narrative for a moment and the underlying arithmetic tells its own story. First half: .302. Second half: .230. September specifically: .140, built on just 6 hits across 43 at-bats — a stretch bad enough that it has dragged his full-season average down to .276 from a first-half peak that had him flirting with .300 deep into the summer. For a hitter who entered 2026 with real helium behind him, a sub-.150 batting average over a six-week stretch is not a slump in the ordinary sense of the word. It is close to the bottom of the outcome distribution for a starting big-league regular.
The September 14 game against San Diego was not an outlier within this stretch so much as a representative sample of it. Batting second and playing right field, Lee went hitless in five at-bats as the Giants were swept in their three-game home series against the Padres — a result that compounded the disappointment of the individual performance with a broader signal about where San Francisco’s season stands heading into its final weeks.
Not a New Slump — a Deepening One
This is not the first rough patch of Lee’s September. Earlier in the month, from September 1 through September 4 — a stretch that included games against the Atlanta Braves and New York Mets — he went just 1-for-21, a .063 average across five games. He caught a scheduled day off, appeared to find something resembling his timing again for a stretch, and briefly looked like a player working his way out of the trough. The 0-for-5 against San Diego, and the sweep that came with it, suggests that recovery was partial and temporary rather than complete. Whatever adjustment briefly steadied him in early September has not held.
That pattern — a brief signal of progress swallowed by a return to the same underlying problem — is often more concerning to evaluators than a single bad week in isolation. A short slump is baseball’s background noise; a month-plus of sub-.150 hitting, interrupted only briefly, points toward something more structural in a hitter’s approach, timing, or health that a day off alone is not going to fix.
It is worth being precise about what is and is not established here. September batting averages, by themselves, are famously noisy — a month is a small enough sample that any regular player can post an ugly average over three or four weeks purely through bad luck on balls in play, with no real change in underlying performance. What separates Lee’s case from ordinary monthly noise is the second-half trend line surrounding it: the drop did not begin in September, it began at the All-Star break, sliding from .302 to .230 across the second half before falling off further into September specifically. A single bad month is noise. A single bad month sitting at the bottom of a two-and-a-half-month decline is a trend.
The Exact Opposite of Last Year
What makes 2026 genuinely strange, rather than simply disappointing, is how precisely it inverts the shape of Lee’s rookie season. In 2025, Lee opened his MLB career slowly, hitting just .249 in the first half as he adjusted to major-league pitching, ballparks, and travel after a standout KBO career with the Kiwoom Heroes. He then caught fire in the second half, climbing to .293, and kept climbing into September, when he hit .315 — arguably his best month as a professional at the highest level, arriving at the moment analysts most associate with a rookie finally “figuring it out.”
2026 has run that exact sequence in reverse. A hot first half established real expectations — a .302 average through the year’s midpoint is All-Star-caliber production for most outfielders — before a second-half decline set in and then accelerated into a September collapse rather than a September breakthrough. Baseball analysts sometimes talk about a “sophomore slump,” the tendency for a strong rookie season to be followed by a disappointing follow-up as opposing pitchers adjust to a hitter’s tendencies. What Lee is experiencing looks almost like a compressed, single-season version of that phenomenon: an adjustment period that arrived not between his first and second years, but within his second year alone, front-loaded with success and back-loaded with exactly the kind of prolonged cold stretch that ordinarily needs an entire offseason to shake off.
A Season Ending on a Difficult Note for San Francisco, Too
Lee’s individual numbers are unfolding against the backdrop of a Giants team whose own 2026 season has grown increasingly difficult in its final stretch. The three-game sweep at the hands of San Diego is not, by itself, a verdict on San Francisco’s postseason chances — the mathematics of a playoff race are rarely settled by a single series in mid-September — but it fits a pattern of a club that has struggled to sustain the form that made it competitive earlier in the year. For a roster built in part around Lee’s bat in the middle of the lineup, his second-half decline and the team’s late-season stumbles are not unrelated storylines; a Giants offense missing consistent production from one of its most talented hitters is, unsurprisingly, an offense that has had a harder time manufacturing the runs needed to close out a tight race.
None of that means the season is decided. The Giants’ final postseason positioning remains to be determined by the games actually played in the season’s last weeks, and it would be premature to describe their October hopes as finished based on results through mid-September alone. What can be said with more confidence is that San Francisco needed its best version of Lee Jung-hoo for exactly the stretch of games in which it has instead gotten one of the worst six-week stretches of his young MLB career.
The sweep itself illustrated the broader problem in miniature. A three-game series lost at home is rarely about one player alone, and San Diego’s pitching staff deserves its share of credit for a series in which San Francisco’s lineup as a whole struggled to generate consistent traffic on the bases. But a lineup missing sustained production from a hitter who was, five months earlier, one of its most reliable on-base threats is a lineup with a smaller margin for the kind of pitching performances San Diego delivered across those three games. In a tight late-season race, series like that one tend to be remembered less for any single dramatic moment and more for exactly this kind of quiet, compounding attrition — one hitless line after another, from a player capable of far more, arriving at the worst possible point on the calendar.
What to Watch From Here
For a player whose first professional season in the United States ended with a September hot streak, the obvious question hanging over the next two or three weeks is whether history can repeat itself in reverse one more time — whether the adjustment that eventually clicked for him late in 2025 can click again before the 2026 regular season runs out of games. The raw talent that produced a .302 first half has not disappeared; it produced real, verifiable results for exactly half of this season. The task in front of Lee now is compressing an adjustment that, a year ago, unfolded gradually across an entire second half into whatever is left of this one.
There is also a simpler, more immediate marker worth tracking for anyone following along day to day: whether the .276 season average keeps sliding or finds a floor. Every additional 0-for-4 or 0-for-5 over the season’s remaining games pulls that number down further, while even a modest return to first-half form would stabilize it relatively quickly given how few games remain. Either way, what has already happened between April and mid-September is, by the account of Korean baseball media covering him closely, a season shape none of them have seen from him before — not in his KBO years with Kiwoom, and not in his rookie MLB season a year ago. That novelty, as much as any single box score, is what has turned a batting-average trend line into one of the more closely watched storylines of Lee Jung-hoo’s young major-league career.
Why Korean Fans Are Watching So Closely
Part of the reason this particular slump has generated so much coverage back home has to do with what Lee represents to Korean baseball’s ongoing MLB pipeline. He was not a marginal contributor pushed to the majors on athletic upside alone; he was one of the most statistically decorated hitters in modern KBO history before he ever left, and his early-2025 struggles were read by some skeptics as evidence that his brand of contact-oriented hitting might not translate against a deeper pool of major-league pitching. His second-half rally last September was treated, fairly or not, as a rebuttal to that skepticism — proof that a hitter built on bat control rather than power could still climb an adjustment curve and finish strong. A first half this good in 2026 looked, for a few months, like the next chapter of that same rebuttal, arriving even earlier in the calendar than it had the year before.
The current stretch complicates that story rather than erasing it. One strong half-season and one strong second-half finish are both real, verifiable stretches of major-league production from the same player within a twelve-month span; so is a second-half decline steep enough to have alarmed close observers of his at-bats. All three things are true at once, and it is that contradiction — not a single bad game, and not even a single bad month — that has made “the exact opposite of last year” the phrase Korean outlets have reached for again and again to describe him this week.