Robinson criticized his group's lack of leadership, harped on its inconsistency in practices and questioned its toughness the night before the team's third preseason scrimmage.
"We don't understand it's not one day on, one day off, one practice on, the next practice off," Robinson said. "It's consistency. That comes with maturity and toughness. And toughness starts here in the heart and here. When everything else starts getting weak, the mind gets stronger.
"Right now everything is weak. Our minds our weak. Write it. I want them to hear it."
Arkansas' defense has struggled against the offense throughout preseason camp.
The group, which is loaded with inexperience, has given up big plays through the air and struggled to stop the run in preseason scrimmages. It has led to at least one move with the starting group: Freshman free safety Elton Ford has been working with the starters the past two days in place of junior Matt Harris.
"We're not there yet with our older players," Robinson said. "We have no leadership now in our older players. They don't understand the tempo of what we expect out of them and I'm disappointed in that as is our head coach.
"The thing is, they've got to grow up and do it our way or we're going to move on, period."
The defense is banged up, too. Linebackers Elston Forte, Ryan Powers and Tenarius Wright missed Friday's practice because of injuries. Defensive lineman Antwain Robinson went down early in the practice with what Willy Robinson said was a hyperextended left knee.
He said some players missing time must learn the difference between being "injured" and playing with pain. He said some banged up players on the field are dealing with more pain than those that are missing time.
"That's how you build leadership," Robinson said. "That's how you build toughness. It's not anything other than that. A quality injury you have to respect. It's a matter of when they come back. But our kids have got to understand they have to play with pain. They do. Bottom line."
Robinson also said the coaching staff has shown more emotion on the field this preseason than the defensive players. So he is challenging the defense to change their attitude starting today.
"They're either going to sit down around their neck and their shoulders and go why is he picking on me? Or they're going to bristle up and get after it and do it the way we want," Robinson said. "Now that is the type of player we're looking for. And until we get that, we're not going to be able to go on any further than that."
Robinson Out, Bequette In
The official extent of Antwain Robinson's knee injury was unknown, but the senior left the practice field and didn't return Friday morning.
Robinson, who was working with the second-team defense, was replaced by former linebacker Robert Salinas during the afternoon practice.
Salinas worked opposite defensive end Jake Bequette, who missed nearly a week after sustaining a concussion last Saturday.
"I tried to get those trainers to get me out here about four days ago, but they would not let me come back until I was completely headache free," Bequette said. "The worst part was not being able to sleep and just watching my teammates push through two-a-days without me."
Battle for No. 2
Petrino weighed in on the battle between redshirt freshman Nathan Dick and true freshman Tyler Wilson for the backup quarterback spot Friday morning.
"Tyler Wilson had a very good scrimmage (Wednesday)," Petrino said. "He was very impressive with the way he distributed the ball, his accuracy. He still is behind on the understanding of the offense.
"Nathan knows the offense better, but has not thrown the ball as accurate as he did all spring. So he needs to come out and play well (today). We need to see that."
• The two-deep defensive depth chart had 10 true or redshirt freshman Friday. Two true freshman (Ford and Khiry Battle) and one redshirt (Jerry Franklin) were with the starters.
• Arkansas will hold its Fan Day festivities today from 3-5 p.m. in the Walker Pavilion.
• Petrino said today's scrimmage, which is closed, will include more game-like situations than the previous two. He said the scrimmage will be big for freshmen competing for spots.
"There were some times when the players think they're working too hard, but we need to push through it and recover and do things right. It will pay off. We'll be a well-conditioned football team. Certainly all the work that they've done throughout the entire summer, not just in camp, will pay off for us."
— Coach Bobby Petrino on Arkansas' detailed and demanding practice schedule
Robinson Sounds Off
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