The Oakland Athletics are all but certain to win the American League West title. Unfortunately for Oakland, the team's playoff chances took a hit Saturday, as the A's announced star third baseman Matt Chapman had been placed on the injured list and will undergo season-ending hip surgery. Chapman had not played since Sept. 6 because of hip tendinitis, and he had recently sought a second opinion on his treatment options. The A's recalled outfielder Seth Brown in a corresponding move.

During Chapman's absence, the Athletics have used a committee approach to filling the hot corner. Vimael Machin, Chad Pinder, and Tommy La Stella have all received starts so far. Pinder (91 OPS+) and La Stella (104 OPS+) are the best hitters of the bunch. La Stella, it should be noted, was acquired from the Los Angeles Angels ahead of the deadline. 

Obviously none of the above can fully replace Chapman, in part because he's irreplaceable. In 152 plate appearances this season, Chapman hit .232/.276/.535 with 10 home runs and his typical well-above-average defense. Chapman is a career .255/.336/.503 (127 OPS+) hitter who has 20.9 Wins Above Replacement since debuting in 2017, according to Baseball-Reference's calculations. He was a Gold Glove winner in both 2018 and 2019.

For some perspective on what Chapman's loss means to the A's and their championship hopes, consider the following numbers courtesy of SportsLine's forecast model. With Chapman, the A's had a 21 percent chance at winning the AL pennant, and an 11 percent chance at winning the World Series. Without Chapman, those numbers drop to 17.5 percent and 8.6 percent, respectively.

Matt Chapman
OAK • 3B • 26
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Chapman is the second notable loss the A's have suffered in recent days. It was announced on Friday that left-hander A.J. Puk, one of Oakland's top prospects and someone who was expected to pitch either as a starter or reliever in 2020, would undergo shoulder surgery. It's the second arm-related surgery in three years for Puk, who previously underwent Tommy John surgery in 2018.

The A's entered Saturday with a 28-15 record, the best mark in the AL. They have a seven-game lead over the Houston Astros.