Williams signed a six-year, $54 million contract in 2008, with $26 million guaranteed. Barber signed a seven-year, $45 million contract following the 2008 season, with $16 million guaranteed.
Each player is highly paid and expected to produce, yet their 2009 performances can be considered a disappointment thus far.
Their play will be scrutinized as Dallas enters the regular-season finale at Cowboys Stadium on Sunday against the Philadelphia Eagles with the NFC East division title on the line.
Williams, who is owed $21.05 million guaranteed on his contract, leads the team with eight drops and is third on the team in catches (38). In the past two weeks, he has just two catches for 18 yards with one touchdown and three drops. He isn't ranked in the top 50 in yards or catches in the NFL.
Williams is supposed to be the Cowboys' No. 1 receiver, but it's the play of Miles Austin, who earned his first Pro Bowl nod this week, that has carried the passing game.
Noted for having good hands, Williams' eight drops this season tie a career high, and many are wondering if it's worth keeping him around next season.
It would be difficult for the Cowboys to cut Williams. Dallas gave up first- and third-round draft picks to Detroit for him in 2008. The Cowboys would have to pay Williams close to $9 million next season in bonus money, whether he's on the roster or not.
"Not in Year 1," Williams said when asked if he would get released. "Not in Year 1 of this thing. Now, next year, if this is the same thing going on, then I'll be like, 'Oh [expletive], I've got to get my [expletive] together, but right now, no. It's play ball. I'm good."
This week, Williams indicated that quarterback Tony Romo and offensive coordinator Jason Garrett have lost confidence in him. However, Romo and coach Wade Phillips said they still believe in Williams.
"I think Roy, like everybody on our team, is doing some things really well and is doing some things that he can improve upon," Garrett said. "Again with Roy, it all goes back to approach. You look at the opportunities that a guy gets and [ask], 'How can I do those things better?'"
Since becoming the full-time starter in 2008, Barber hasn't rushed for 1,000 yards and has battled injuries. He ranks 18th in the league in rushing yards this season, and his average yards per carry, which was at 4.4 heading into the game against the San Diego Chargers in December, has dropped slightly to 4.2.
While Barber is still a physical runner, he's not breaking tackles on a regular basis, something that was one of his strengths. A thigh injury, suffered in Week 2, could be the cause, although Barber said recently that he's healthy.
In 2007, his only Pro Bowl season, Barber finished fifth in the league with 10 rushing touchdowns as a backup. He led the NFL with 29 broken tackles, according to Stats LLC. The next year, Barber broke 24 tackles, tied for fifth, but this season he's escaped just eight tackles, tied for 27th.
He's also been stopped 22 times for no gain, with one game remaining in the regular season. Last season, he was stopped 25 times and in 2007 just 14 times.
"I don't see him being less physical as a runner," running backs coach Skip Peete said. "I don't see him any different than he's been the last couple of years."
Barber had performed well in short-yardage situations until his most recent game. On the season, he's produced 10 first downs out of 17 carries on third- and fourth-and-1 plays. But last week, Barber struggled to gain a yard on four short-yardage plays. In the previous week, a victory over the New Orleans Saints, Barber gained first downs on two short-yardage plays.
Barber declined to speak with a reporter this week about the short-yardage plays. At times, he's playful with reporters, but his lack of accessibility leaves others answering for him.
"He's our guy," inside linebacker Bradie James said. "He knows we rely on him. He's had to step back some [because he shares carries with Felix Jones] and get in there to just make the most of his opportunities."
Starting Sunday, the play of Barber and Williams must improve to help the Cowboys succeed. If not, the questions will continue to linger over both.
"I have to take my game to another level," Williams said. "I have to do that, and it starts this Sunday and this is pretty much a playoff game for this football team. Hopefully, I can win the confidence of my peers here and the fans and even my family. They were getting on me. My brother is getting on me hard, and my mom is getting on me. I've got to get these people off me, and the only way I can do that is play my game."