IRVING, Texas – Once again, the Dallas Cowboys are Matt Cassel's team.

This time, however, it is not in a caretaker role. It’s his job with Tony Romo out for the rest of the regular season with a left collarbone hairline fracture.

The Cowboys are keeping Romo on the 53-man roster with the outside shot he could return for a possible playoff appearance. Of course, for that to happen, Cassel will have to deliver, possibly having to win the final five games of the season, starting with Monday’s game against the Washington Redskins.

Cowboys quarterback Matt Cassel was 0-4 during Tony Romo's first injury absence. EPA/Larry W. Smith

“I try not to think of [just holding the fort] when you are playing because you’ve got show these guys that you are going to be assertive, you are going to be a leader out on the field,” Cassel said. “At the same time, with Tony not coming back, my leadership needs to step up even more. I need to be more assertive, and hopefully that will help us.”

Cassel’s first turn as the Cowboys’ starter didn’t go the way he or the Cowboys hoped. They lost all four games. In two of the games, the offense did not generate a touchdown. In two of the games, Cassel didn’t pass for 200 yards. In two of the games, he had interceptions returned for touchdowns.

He did all this in an offense he had not seen until the Sept. 23 trade from the Buffalo Bills.

“The challenge is being thrown in,” coach Jason Garrett said. “There’s so many nuances and details of playing that position and understanding the system, understanding the guys you’re playing with, the communication beyond what’s written on the page. He’s an experienced guy, been around a lot of offenses. He’s played a lot of football, but understanding how we do it and understanding the guys he’s playing with his critical. I think we’ve seen him grow and develop in so many areas over the course of the four games that he played. He got better and better because he was more experienced in this environment.”

But the Cowboys hope the experience Cassel gained by watching Romo in 104 snaps against the Miami Dolphins and Carolina Panthers will help even more.

While Romo's performances weren't flawless, they gave Cassel a chance to see how Romo orchestrates things in an offense he knows so well.

“The little nuances to it, or the cadences, the simple things that he does at the line of scrimmage, some of the protections that he was able to get to, it was great for me to see that and see that in person,” Cassel said. “Because when you’re watching it on film, you’re just watching a cut-up reel or something like that. You don’t completely understand it. But when you’re out there on a day-to-day [basis] and watching practice and seeing it in a game, it was very helpful for me.”

When Cassel took over for Romo against the Panthers, he completed 13 of 19 passes for 93 yards and threw a 2-yard touchdown pass to Cole Beasley.

“My comfort level is definitely better than what it was prior to this,” Cassel said.

And the comfort level of offensive coordinator Scott Linehan should be better. Linehan will have a better idea of what Cassel likes and doesn’t like, what he does well and what he doesn’t do well.

“You are always evaluating the position you are putting your guys in,” Garrett said. “Are we playing to their strengths? Are we minimizing their weaknesses? Are we giving them something they are comfortable with? No position [is] more important than quarterback when you talk about that kind of stuff. I do think having time together with him in a game-type situation will benefit everybody.”

When Cassel arrived in the trade -- his second this year after being dealt by Minnesota to Buffalo in March -- his wife was eight months pregnant. She had the couple’s fourth child, Clayton, during the Cowboys' bye week. For a time, the family lived in a local hotel before finding a house. Slowly, everything off the field has come together.

He’s hoping it comes together on the field, starting Monday.

“It’s about as crazy as you could possibly get, especially with everything going on in my personal life with my family and my wife being pregnant and moving from two cities in just a six-month span, being traded twice,” Cassel said. “At the same time, I think that this lifestyle, you have to embrace the craziness of it. I’m just grateful for the opportunity and be able to come out here and be able to play again.”