During the last three months of the 1987 season, a finger on Gwynn's left hand would lock when he gripped a bat. It would come open barely enough for the bat to slip out from his grip. He had surgery on the hand during Spring training the following season. Early in 1988, Gwynn was on the DL for 21 days after spraining his thumb after tripping rounding first base in Pittsburgh. He was hitting .246 as late as July 2, 1988, but won the championship with a .313 average. Gwynn batted .406 in July and .367 in the last 73 games of the season. He denied that injuries impacted his hitting, instead attributing his struggles to "mechanics". He struck out a career-high 40 times that season, while his .313 average was the lowest to win a title in NL history. In the 112 years before, only nine batting leaders hit below .330, the previous low being Larry Doyle's .320 in 1915. For the 25 years ending in 1988, batting leaders averaged .343. Gwynn hit 119 points higher with runners on base (.382) than with the bases empty (.263), the largest differential in the NL that season. He tied Pedro Guerrero for the highest average with runners in scoring position (.371). During the season, McKeon replaced Bowa as Padres manager, and moved Gwynn from right to center field. Gwynn also reached 1,000 career hits on April 22 with a single off Nolan Ryan of the Astros. On September 17, he passed Dave Winfield as the Padres career leader in hits with his 1,135th off Jim Acker of the Atlanta Braves.