Robinson wasn't with the Cowboys this summer, having spent his time in San Diego before being released by the Chargers after their last preseason game.
His presence here has turned out to be a good thing for the Cowboys, who needed a veteran receiver to provide insurance in case one of their other receivers suffered an injury or regressed in his development.
Robinson has filled that role.
In six games, Robinson has two 100-yard games, caught the longest touchdown pass of the season for the Cowboys and has five receptions of 20 or more yards.
Robinson isn't considered a typical free agent. He's what people in the business refer to as a street free agent, a player let go by a team just prior to, or during, a season. These players spend time waiting by the phone as their agents arrange workouts with various NFL teams.
Robinson had to stay in shape because he never knew when the phone would ring from a team seeking to add to its roster.
He wasn't alone.
"That's their jobs as vets," veteran linebacker Bradie James said. "You get to a point in your career that if you're on the street, you better know how to play some ball when you get to wherever you're going. Those guys step in, and we don't miss a beat. [Robinson] has been injured a lot, and he and I talked about that the other day. It's just great that he can put together a lot of good games and be accountable and be a pro about it. He's definitely stepped up."
Players become street free agents for a number of reasons. In Robinson's case, it wasn't because he couldn't play. He was a third-round pick by San Diego in 2007 after leaving Illinois State with school records for catches (192) and total yards (3,007). The injury bug held Robinson back.
After his rookie year, Robinson played in only six games before a hamstring injury forced him to injured reserve in 2008. He was traded to St. Louis in 2009, playing three games before an ankle injury put him on injured reserve in late September.
Robinson found some success in 2010. He played 14 games, starting 11, and finished with 34 catches for 344 yards and two touchdowns. He caught then-rookie quarterback Sam Bradford's first career touchdown pass.
Robinson was released after the season and signed with San Diego this summer. The Chargers, with a logjam at receiver, cut Robinson on Sept. 3.
Enter the Cowboys.
Coach Jason Garrett was attracted to Robinson's ability to absorb information quickly, as well as his route-running and catching skills. Garrett's numbering system used in calling routes for receivers is similar to San Diego's, which also helped in the process.
But after signing with the Cowboys on Sept. 7, Robinson suffered a hamstring injury the first day he practiced. The Cowboys valued Robinson but needed to move quickly. He was cut Sept. 13.
"It was real frustrating the first day that happened," Robinson said of his injury. "I was patient enough and I got healthy and I was able to get out there."
The Cowboys returned a healthy Robinson to the roster Sept. 20, two days after veteran receiver Miles Austin reinjured his left hamstring.
Robinson caught three passes for 49 yards in his first game with the Cowboys that week.
"He's been well coached," quarterback Jon Kitna said of Robinson. "I think that is one of the things we noticed when he got here, running routes, things like that. You can tell he's been trained well along the way. He's had some good coaches that hammered in the details."
It's a good thing for the Cowboys, whose projected No. 3 receiver -- Kevin Ogletree -- has struggled. With defenses trying to keep Austin and Dez Bryant in check, Tony Romo has relied on Robinson to produce in the passing game.
As the season progresses, the Cowboys will continue to call Robinson's number, especially with Austin expected to miss two to four weeks with a right hamstring injury.
It's quite possible Robinson will start Sunday afternoon versus the Buffalo Bills.
"I take pride in knowing what I'm doing and knowing where I'm supposed to be at," he said. "I want to make sure I know my assignments and go the right depth on the routes and try to make plays on the ball so they can have confidence in me."
The Cowboys are counting on it.
Calvin Watkins covers the Cowboys for ESPNDallas.com.