Jones said he heard as much from offensive coordinator Greg Olson, who held the same position when Jones played in Oakland in 2014.
"I just had a chance to speak with Coach Olson, and he said talent-wise, there's probably nobody that can compete with talent-wise," Jones said. "But they said he's not picking up the playbook, and that's the reason of a little frustration right now, because they want to get him on the field, but he's not able to grasp the playbook yet."
Jones added that to streamline the learning process, the coaches have had Bryant working at just one position, rather than moving around and learning the X, the Z and the slot like the team's other wideouts have been doing.
"They've only got him lining up in one spot to try to slow it down and help him out," Jones said. "They need him to pick it up."
Gruden expressed frustration with Bryant -- whom the team acquired from the Pittsburgh Steelers for a third-round pick in April's draft -- while speaking to reporters on Saturday, saying, "He's got to get out here and play better."
"He's in a competitive situation," Gruden continued. "Right now, a lot of the other receivers have had a nice camp. He's just got to learn the offense. He's got to stay out here. He's had some illnesses. He's got to get on the field. He's got to master the offense and become more versatile, and that's the key to making this team better."
Bryant also missed a practice last Wednesday with an illness.
The 26-year-old is part of an overhauled wide receiving corps that includes veteran free agent signing Jordy Nelson and trade acquisition Ryan Switzer, who was a fourth-round pick by the Dallas Cowboys in 2017. The primary holdover is Amari Cooper, who has been lining up all over the field throughout the offseason.
Bryant finished 2017 with 50 catches for 603 yards and three touchdowns, getting benched and temporarily demoted to the scout team in favor of JuJu Smith-Schuster, whose emergence made Bryant expendable in Pittsburgh. Bryant racked up 1,363 scrimmage yards and 15 total touchdowns in 21 games from 2014-15, but he missed the 2016 season with a suspension for violating the league's substance-abuse policy.
A report in June said the team feared another suspension for Bryant, but none has been announced to this point.
A fourth-round pick in 2014, Bryant will make $1.9 million this season in the final year of his rookie deal before hitting unrestricted free agency in the spring.
--Field Level Media