If a player switches leagues, can he still win a batting title? It's complicated

With both Luis Arraez and Otto Lopez in the rumor mill leading up to Monday’s Trade Deadline, you may be wondering how a trade could impact either player’s pursuit of a batting title.

In order to win the American or National League batting title, a player must finish the season as a qualified hitter within that league. That means he must reach 502 plate appearances -- 3.1 per team game -- while either playing as a member of an NL or AL team. And while we recognize which batter leads the Majors overall each year, there isn’t a specific MLB batting title. A batter must qualify in a specific league in order to win a batting title.

If a player is traded within his league, there’s no issue. He continues to add on to the stats he had prior. Indeed, four players have won batting titles in seasons where they played for multiple teams in a league: 2024 Arraez, 2021 Trea Turner, 1947 Harry Walker and 1932 Dale Alexander.

But if a player is traded from one league to another, things can get complicated. On his stats page, numbers continue to accumulate like usual. But in terms of batting titles, or leading a league in any individual rate stat, only the numbers from his time in that league count. If the player already reached the qualifying threshold, he stays in that league leaderboard as is. If he did not reach qualifying totals, he will eventually fall off the league leaderboard, even if he continues to be qualified MLB-wide.

There are numerous potential implications here. First, there’s the batting title race itself. But there’s further consideration with a player like Yordan Alvarez chasing a Triple Crown. If traded to the AL, neither Lopez nor Arraez would accumulate enough plate appearances in that league to compete for its batting title, so they would not preclude Alvarez from winning.

But either could stand in the way of Alvarez becoming the first player since Mickey Mantle in 1956 to lead all players in all three Triple Crown categories, since Lopez and/or Arraez would still be qualified overall.

That means we could see a player lead MLB in batting average and not win a batting title.

Wait, what? Let us explain in more detail. It’s one of baseball’s most fascinating recordkeeping quirks, and it involves a fun history lesson, too.

Has this happened before?
There’s been one player to lead the Majors in batting average and not win a batting title in the modern era (1900): Eddie Murray in 1990.

Murray didn’t change teams, but instead lost out on a batting title because another player changed teams. Here’s what happened.

Murray hit .330 for the Dodgers, finishing a point ahead of the Royals’ George Brett for the MLB lead. Brett won the AL batting title. But Murray finished five points behind another player for the NL batting title -- despite leading the Majors overall.

Enter: Willie McGee. He hit .335 in 542 plate appearances for the Cardinals, through Aug. 29. That day, he was traded to the A’s, where he finished up the season. He hit .274 in 123 plate appearances in Oakland, finishing with a .324 average overall.

But since he was traded across leagues, that .335 average in the NL froze the moment he put on an A’s uniform. And since he was traded in August and had accumulated enough plate appearances to be qualified at the end of the season, he led the NL in batting average and won the batting title. Despite finishing the season in an A’s uniform, and with an overall batting average below Murray’s .330.

What about counting stats?
While rate stats involve qualifying, as noted above, there’s more potential history with cross-league stats if we look at counting figures. Namely, stolen base totals for Starling Marte in 2021, when he was traded from the Marlins to the A’s. Overall, he led MLB with 47.

But if we break it down by league, it gets fascinating. His 25 stolen bases with the A’s were tied for sixth in the AL. And his 22 with the Marlins before the trade? That figure still ranked fifth in the NL.

No player had ever finished even in the top 10 in stolen bases in both the AL and NL in the same season before Marte, according to the Elias Sports Bureau.

The researchers at Elias were kind enough to dig through other ‘whole number’ stats -- hits, doubles, strikeouts, and so on -- to see if anyone had ever finished top-10 in both leagues in any of them before Marte in 2021. The only one they could find was complete games by pitchers.

In 2009, Cliff Lee was tied for fifth in the AL in CGs with Cleveland and tied for third in the NL with the Phillies after a trade. The year before, CC Sabathia led the NL in complete games with the Brewers, and was tied for third in the AL with Cleveland, with those accumulated before the trade. In 2002, Bartolo Colon finished tied for fourth in the AL in complete games with Cleveland, and was tied for fifth in the NL with the Expos after a trade. And in 1998, Randy Johnson finished tied for eighth in the NL in complete games with the Astros after a trade, with his AL total with the Mariners beforehand ending up tied for fifth.

There’s some precedent for this concept, but not very much.