The decision presumably means that Matt McGloin isn't healthy enough to play.
McGloin, 27, suffered a left shoulder injury in Oakland's regular-season finale against the Denver Broncos that forced him out of the game late in the second quarter. He was just 6-of-11 for 21 yards as Oakland went into the half trailing 17-0. Cook played the second half, finishing 14-of-21 for 150 yards, one touchdown, one interception and a lost fumble.
The Raiders lost to the Broncos, 24-6, and lost both an AFC West title and bye week in the process.
While McGloin played poorly against Denver, he has four years of experience in Oakland and two years with Jack Del Rio's system, while Cook appeared in his first NFL game against the Broncos and hadn't even been active before Sunday.
Cook, 23, likely has more of an upside in the future than McGloin presents. What remains to be seen is if he'll give the Raiders a chance to win against Houston.
He gave himself mixed reviews for his performance against Denver.
"I thought I made some good throws," Cook told the media, per Des Bieler of the Washington Post. "Obviously put the ball on the ground too many times and I gave them one with the interception. But it's a learning experience. We're going to put this behind us and focus on next week."
For the Raiders, turning to Cook is ultimately a disappointment but a necessity after Oakland lost franchise quarterback Derek Carr for the year with a broken leg. Carr was an MVP candidate given his excellent play in the 2016 season and had the Raiders positioned as legitimate Super Bowl contenders.
With Cook under center, however, the Raiders may not even be able to escape the Wild Card Round.
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