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The San Francisco Giants placed lefty Blake Snell on the injured list on Wednesday, just hours ahead of his scheduled start against the New York Mets. Snell, dealing with a left adductor strain, was replaced on the 26-player roster by right-hander Landen Roupp. The Giants will open with Ryan Walker as part of a bullpen game.

Snell, 31, is the reigning National League Cy Young Award winner. He signed with the Giants in mid-March following a overextended stay on the free-agent market. In three appearances to date, he's amassed an 11.57 ERA (35 ERA+) and a 2.40 strikeout-to-walk ratio. Snell has yet to complete five innings in a start.

According to Baseball Prospectus' recovery database, players suffering from adductor strains miss 29 days on average. Every pitcher and every injury is different in its own way, meaning that Snell may end up missing more or less time. Still, it's possible that the Giants will be without Snell for about a month, give or take.

Snell is the fourth Giants starter to be placed on the IL. He joins fellow lefty Robbie Ray (recovering from Tommy John surgery) and righties Alex Cobb (hip surgery) and Tristan Beck (vascular surgery). It's unclear who the Giants will plug into Snell's place next time through the rotation. In theory, the most obvious candidate might be Daulton Jefferies, who is already on the 40-player roster and made a spot-start earlier this year. (It should be noted that Jefferies' start did not go particularly well.)

Roupp, 25, has made eight relief appearances with the Giants. He's compiled a 4.35 ERA (94 ERA+) and a 1.75 strikeout-to-walk ratio. 

The Giants enter Wednesday with a 12-13 record on the year. That puts them in a tie with the Arizona Diamondbacks for third place in the NL West. They're two games back of the division-leading Los Angeles Dodgers.