Cardinals tackle D.J. Humphries works against the Chargers in Saturday night's preseason game.

D. J. Humphries has had a rough training camp. If you weren't watching practices, it was clear nonetheless by the comments from coach Bruce Arians.

First there were the chuckles by Arians revealing the tackle's nickname as "Knee Deep," because a foot up Humphries' backside wasn't providing enough motivation. Then last week, while talking about the professionalism of tackle Bradley Sowell, there was a jab at Humphries.

"(Sowell) shows up every day," Arians said. "D.J.'s a rookie. He shows up once every week."

Then Saturday, Humphries didn't play well in a preseason game against the Chargers, and Arians was definitely not happy on a sack Humphries

allowed: "Bad technique and bad effort," Arians said. "He got outfought. Simple as that."

It has not been the kind of start Humphries was hoping for in the NFL, nor the start the Cardinals hoped from their first-round draft pick. Three weeks of training camp and two preseason games do not a draft pick make, of course, and much can change even before the start of the regular season.

But it's hard not to notice a first-round pick who, at this point, will be unable to find playing time once games start to count.

Humphries was unavailable for comment.

"I'm 21, so I knew it was going to take some maturing when you're on the field with guys who've got wives and full families, you know what I mean?" Humphries said earlier in camp. "So it was just a stepping stone.

"I feel like I'm getting it and I'm starting to understand."

Arians said Monday Humphries will work at left tackle this week, allowing Earl Watford to get snaps at right tackle as Watford tries to battle Bradley Sowell for the starting job. Humphries needs the left-side work, Arians said, because it'll be necessary in his immediate role.

"He's going to be a backup tackle for us," Arians said, "so if he's going to dress on Sundays, he's got to be able to play

both."

That's a far cry from the hope that Humphries might be able to beat out Bobby Massie as the starting right tackle. The Cardinals are fortunate because they have options beyond Humphries.

Then again, a slow start for a rookie tackle isn't altogether surprising. Humphries is only 21 years old, and was told before the draft he'd be better served to stay in school one more year. It's not like the Cardinals overdrafted him – there was a great chance the Panthers were set to choose him one slot later had the Cards not called his name – but there was always the feeling Humphries was raw.

Humphries isn't the first recent first-round tackle to start his NFL career slowly. Eric Fisher, Luke Joeckel and Lane Johnson, all top four picks two years ago, struggled mightily as rookies. Jake Matthews had a tough time early last season.

"He's a guy that on one play looks exactly like the first-round pick we selected," General Manager Steve Keim said on Arizona Sports 98.7. "He's got great feet. You don't find many offensive tackles with that lateral quickness and the ability to slide and mirror in pass protection.

"At the same time he doesn't do a great job with his hands and needs to get better with his punch. The bottom line is his consistency. His technique is up and down and I know coach Arians has been hard on him and will continue to stay hard on him. We have high expectations for DJ."

Humphries has repeatedly said he will work hard to get where he needs to go.

"If you're going to do something you're going to do it to the best of your ability," Humphries said in June. "If it doesn't work out for me then, I'm confident I'll have given it my best shot."

Arians had called into question Humphries' maturity earlier. A first-round pick isn't going anywhere for a while. Humphries has time to learn, although the spotlight will remain – he is a first-round pick, after all.

"He's got to improve," Keim said, "and he's got to improve fast."