Starting quarterback Alex Smith broke the tibia and fibula in his right leg during Sunday's 23-21 loss to the Houston Texans. McCoy, in his fifth season with Washington, will start in Smith's place, but the Redskins had no other quarterback on the roster or even on the practice squad. They opted for Sanchez from a group that included E.J. Manuel, Kellen Clemens, Josh Johnson and T.J. Yates.
Sanchez does have several ties to Washington from his five years with the New York Jets. Redskins passing game coordinator Kevin O'Connell was a backup quarterback for parts of three seasons with the Jets during Sanchez's time there. Redskins offensive coordinator Matt Cavanaugh was the Jets' quarterbacks coach from 2009 to 2012. And Redskins offensive line coach and assistant head coach Bill Callahan held the same title for three seasons during Sanchez's Jets tenure.
Redskins head coach Jay Gruden said that familiarity was part of the team's decision to go with Sanchez.
"We had a workout today; looked pretty good," Gruden said Monday. "But [it's] based on his past experiences with Coach O'Connell and Cavanaugh. He's won some playoff games, he's got a lot of experience. I think this time of the year, you need somebody who's taken some meaningful snaps, [with] a lot of experience, and Mark's done that."
Sanchez, the fifth overall pick in the 2009 draft, has started 72 regular-season games and six more in the postseason. He has thrown 86 touchdown passes and 86 interceptions during his career and owns a career 73.9 passer rating and a 40.2 QBR.
The Redskins have been one of the NFL's best teams at taking care of the ball this season, with only nine turnovers. In 2011-12 -- his last two seasons as New York's starter -- Sanchez threw a combined 36 interceptions and fumbled 16 times. One of those turnovers became known as the "Butt Fumble," a play in which Sanchez lost the ball when he slammed into a lineman's backside. That occurred during a Thanksgiving Day game versus the New England Patriots on Nov. 22, 2012; six years later to the day, he'll suit up for Washington for the first time when the Redskins play at Dallas.
Sanchez also has played for the Eagles and Cowboys and spent time on the rosters of the Bears and Broncos.
Sanchez is 4-2 in the postseason with a 71.5 total QBR a 95.5 passer rating with nine touchdown passes and three interceptions. He helped the Jets reach the AFC Championship Game twice.
Gruden also updated Smith's status on Monday, saying surgery went well and that a full recovery is expected.
A source told ESPN's Adam Schefter that Smith suffered a compound fracture (the bone broke through the skin) and a spiral fracture (a long bone being broken by a rotational force).
Smith did not suffer any ligament damage, Gruden said, and the coach believes Smith is looking at a timeline of "six to eight months" for recovery.