ALAMEDA, Calif. (AP) When Amari Cooper arrived at practice this week for the Oakland Raiders, he immediately was drawn to a special guest instructor.
''My first reaction was he's huge. I can understand why they call him Megatron,'' Cooper said. ''He definitely lives up to that.''
Former Detroit Lions great Calvin Johnson is spending the week at practice with the Raiders as the guest of offensive coordinator Todd Downing, giving tips to Cooper and the team's other receivers and answering questions about what made him so successful in his NFL career.
Downing was an assistant in Detroit for five seasons when Johnson was one of the league's most feared receivers. Johnson finished with 731 career receptions for 11,619 yards, a league-record 86.1 yards receiving per game, and 83 touchdowns against defenses often geared to stop him. He also set the single-season record with 1,964 yards receiving in 2012.
All that came after the Raiders memorably passed up the chance to draft him with the No. 1 overall pick in 2007, taking bust quarterback JaMarcus Russell instead.
Ten years later, he was on the practice field with the Raiders as a coach rather than a player.
''Todd invited him out, thought it would be a great idea for our wide receivers to just pick his brain and have him be around and give us a point here or there and talk about some of the things he did so well in his career and how we might be able to have some of our guys learn from that,'' coach Jack Del Rio said.
Cooper knows he will never have the physical tools that made Johnson so successful as a 6-foot-5, 239-pound receiver who was clocked at 4.35 seconds in the 40-yard dash.
But he still wants to get as many tidbits out of Johnson as he can.
''I've just been asking him a whole bunch of questions,'' Cooper said. ''How does he run certain routes? What was his regiment like and how was he so productive? He's a really great guy. He's given me really great feedback so he's really great to have around.''
Cooper has had one of the most productive starts to a career of any wide receiver. After catching 70 passes for 1,070 yards as a rookie, he improved to 83 catches for 1,153 yards last season.
He became just the third player to start his career with back-to-back seasons with at least 70 catches and 1,000 yards receiving after Odell Beckham Jr. and Marques Colston.
But Cooper's production has fallen late in both seasons as he was hampered by injuries as a rookie and dropped off again in the second half last season.
Cooper averaged 6.6 catches for 98.4 yards per game in the first half of 2016 before getting just 3.9 catches and 45.8 yards per game in the final eight weeks.
''Of course it's been on my mind,'' he said. ''It's a good thing for me because I feel like I can go nowhere but up. I know I can have a lot more production than I've had the last two seasons.''
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