The Bears liked receiver Darnell Mooney enough to trade back into the fifth round of this year's draft to select the Tulane receiver.

If anyone thought that Mooney would see more playing time than any receiver other than Allen Robinson II by the third game of his career, they certainly didn't express that thought at the time.

So when did the Bears coaching staff realize that Mooney would be able to handle a veteran's workload so early in his career?

"To tell you the truth," said coach Matt Nagy, "it was probably the first day we came out here on grass and actually watched him, and we knew, 'OK, yeah, this one's real.' It was pretty neat to see because you see it on tape, and you never really know."

With limited opportunities to see Mooney over the summer, Nagy watched the rookie pass test after test.

"That's what's so beautiful about the offseason," said Nagy. "You're able to see guys that you hit on or maybe you missed on. You get a feeling for it. Then in training camp, you have a pretty good idea of what you're going to do. We didn't have that, so the first time we got to training camp, and we saw the way that he ran routes and the way that he caught [the football], his personality. The next question was, 'OK, great. [He] looks good in shorts and a t-shirt, but what about when pads come on?' And then the pads came on, and he kept doing it. And he kept doing it."

Mooney has recorded eight catches for 93 yards and a touchdown, putting him in the top 10 for receptions amongst rookies in a loaded receiver class. Nagy believes that Mooney still has a lot left in the tank.

"This kid, like, he never gets tired," said Nagy. "It's unbelievable. The kid just runs and runs and runs. We had to pull back in training camp to not overcook his legs."

Nagy referred to Mooney's increased role as the "next test" that he expects the rookie will meet the challenge.

Stepping up: With Tarik Cohen on injured reserve, the Bears added undrafted rookie running back Artavis Pierce to the active roster on Tuesday.

Pierce rushed for 873 yards and six touchdowns during his senior season at Oregon State, averaging 6.0 yards per carry.

"I think he's got really, really good vision, patience in the hole," said Nagy. "We're continuing to keep working on his ball skills coming out of the backfield. He's a great kid, he learns well, he learns fast."

Running backs coach Charles London said Monday that he expects Ryan Nall, a former Oregon State teammate of Pierce, to partially fill in for Cohen, but Nagy believes Pierce will make the most of his opportunity.

"We didn't draft him," said Nagy, "but our personnel did a great job of finding him and now bringing him in here. Now, you get a guy that has an opportunity and who knows how much or what he'll get [in terms of playing time], but shoot, I know this: He's done everything that he possibly could have done to this point to do good things and impress us, and we like that."

Pierce may emulate Cohen's elusiveness more than Nall, who is known more as a power runner. Pierce sees some similarities between himself and Cohen, but Pierce is much bigger, listed at 5-11 and 208 pounds.

"I really love [Cohen's] game," said Pierce. "He's explosive; he can run the ball. He can run routes and stuff like that. At this level, that's what it takes to be a running back. You have to be able to catch the ball and run the ball. I can do a little bit of that. I'm not as shifty as him, but I got a little shiftiness to do the same thing."

Working back: Kicker Eddy Piñeiro has been on injured reserve for three weeks, which, under this season's rules, makes him eligible to be reactivated.

Piñeiro has been sidelined with a groin injury. On Wednesday, Nagy left things open about when Piñeiro would return.

"I think honestly with him, they're still working through some things," Nagy said. I don't know if we're there yet right now this week. That's stuff that 'Dre' [head athletic trainer Andre Tucker] will fill me in on, so I don't have a definitive answer for you right now, but I think things are definitely getting better."

Last year, Piñeiro made 23 of 28 attempted field goals, including a game-winning 53-yarder against the Denver Broncos in Week 2.

In his absence, Cairo Santos has hit 4 of 6 field goal attempts.

Injury report: The Bears held six players out of practice Wednesday. Defensive back and special teams mainstay Sherrick McManis did not participate due to a hamstring injury, while four players—receiver Ted Ginn Jr., tight end Jimmy Graham, offensive tackle Bobby Massie, defensive lineman Akiem Hicks and linebacker Danny Trevathan—did not practice under the "Non-injury/resting veteran" designation.

Linebacker Khalil Mack and safety Deon Bush were limited due to groin and knee injuries, respectively.

Three players were listed on the report but practiced without restrictions: safety Tashaun Gipson Sr. (neck), running back David Montgomery (wrist) and linebacker Josh Woods (ankle).