Sanchez is the team's starter for the foreseeable future after Nick Foles fractured his collarbone against the Houston Texans on Sunday, an injury that will reportedly keep him out six to eight weeks.
According to the Philadelphia Inquirer, Kelly said he believes Sanchez will be a quality replacement for Foles.
"I feel great about Mark," Kelly said Monday. "I thought he's done a great job in our system. I thought he played outstanding in the preseason and showed no rust or anything when he got in there against Houston yesterday. So we feel real confident and feel obviously very bad for Nick that he's out, but I feel very confident in Mark."
"I think he obviously has a big-time arm, an NFL arm, he's got NFL feet," Kelly said to the Inquirer. "He's really, really smart. . . . Great work ethic, very athletic, all the things you're looking for in a quarterback."
Sanchez came in for Foles after Foles sustained his injury in the first quarter against Houston and led the Eagles to a 31-21 win, going 15-for-22 for 202 yards, two touchdowns and two interceptions. His first play was a 52-yard pass to receiver Jeremy Maclin.
The former No. 5 pick in the 2009 NFL draft, Sanchez started 62 games and six playoff games from 2009-12 for the New York Jets, helping take the team to the AFC Championship Game in each of his first two season. He fell out of favor in New York, though, due to his high volume of turnovers and the team's inconsistent offense.
After throwing 18 interceptions and finishing with a 66.9 quarterback rating in 2012, Sanchez lost his starting job and played in just six games for the Jets last season, partially due to a shoulder injury. The team released him after the season and he signed with the Eagles to be their backup.
Foles, 25, has thrown for 2,163 yards, 13 touchdowns and 10 interceptions this season while completing 59.9 percent of his passes.
The win over the Texans improved the Eagles' record to 6-2. Philadelphia is in first place in the NFC East.
- Ben Estes