PHILADELPHIA (AP) – Juan Castillo's eyes got red and watery and his voice quivered slightly when he was asked if he ever lost confidence in himself during his struggles as a first-time defensive coordinator.

"The only thing for me is: I don't want to fail my head coach," Castillo said. "I don't want to fail him, man. I don't want to fail my boss."

The Philadelphia Eagles aren't going to the playoffs for the first time since 2007 and just the fourth time in coach Andy Reid's 13 seasons.

Since his surprising switch to defensive coordinator after 13 seasons coaching the offensive linemen, Castillo has been under the microscope in Philadelphia. Every call, each move has been scrutinized intensely.

So when the defense played poorly and the Eagles started 1-4, Castillo got ripped from every corner.

It's no surprise then that heading into Sunday's season finale against Washington there's speculation about Castillo's job. Some think Castillo will be handling the defense for the last time. One report earlier this week had St. Louis Rams coach Steve Spagnuolo replacing Castillo.

Spagnuolo was an assistant with the Eagles from 1999-2006 under defensive coordinator Jim Johnson. He spent two seasons as the defensive coordinator for the New York Giants winning a Super Bowl in 2008. Spagnuolo then moved to St. Louis in 2009. The Rams are 2-13, so Spagnuolo might get fired.

All Castillo cares about is right now.

"I just want to see us keep getting better," he said. "I think that going through the year we started slowly and that's not the way we wanted to start. But we're finishing up where we wanted to finish up and we wanted to be able to do some of the things that we're doing."

Players defended Castillo all along, saying they just needed time to adjust to his system.

"I think it's a lot more experience with everybody playing together," defensive tackle Cullen Jenkins said. "I think people are really stepping up and making plays when they're put in a position to. As for earlier in the season, we weren't doing that very well. And obviously, when that happens, it all reflects on the coaches. The players have just stepped it up more. We were put in a good position earlier and we didn't come away with the plays or the victories when we needed them."

The defense has improved significantly during the Eagles' three-game winning streak. They've held opponents to 36 points and 683 total yards. They also have 16 sacks in that span.

"I think from a player's standpoint, I think you see consistency," Reid said. "I think what he told you happens, and he's aware of it, knowing the players, playing to their strengths, and covering up whatever weaknesses they have. I think the part that he's been consistent, he's not afraid to admit a problem and fix the problem."

Castillo was hired after the Eagles already had brought in former Tennessee defensive-line coach Jim Washburn to implement his wide-nine scheme.

Even players were taken aback when it happened. Cornerback Nnamdi Asomugha recently said that his teammates didn't have much confidence in Castillo's calls early in the season, but now they are executing better because they believe in him.

"New coaches, new system, new players and with more time, the better we get," cornerback Asante Samuel said. "We get to evolve and everybody gets to know each other better and understands what your job in the defense is. So everybody's learning, growing more, and getting comfortable."