Philadelphia Eagles wide receivers coach Mike Groh believes Alshon Jeffery had his best offseason since perhaps 2013, when Jeffery burst onto the scene and set career highs in catches (89) and yards (1,421) while finding the end zone seven times.

Groh would know. He was the Chicago Bears' receivers coach for three seasons (2013-15), which proved to be the most productive years of Jeffery's career to date. Groh moved on to coach the Rams' wideouts last year while Jeffery struggled through a down season as the result of injuries, a four-game suspension for violating the league's policy on performance-enhancing drugs and inconsistent quarterback play.

The two have reunited in Philly, and Groh -- a demanding teacher and evaluator -- walked away pleased with Jeffery's performance during the offseason training program.

Alshon Jeffery had his best NFL season under WRs coach Mike Groh, who joined the Eagles' staff this offseason. Photo by John Jones/Icon Sportswire

"He and I have a history together, so he knows what I think, and I understand the way that he works and goes about his business," Groh said. "I think the spring that he's had is as good as he's had since maybe 2013. Pleased with where he is physically, mentally I think he is in a good place. He's coming in here and learning a new system and working on the chemistry with Carson [Wentz] and everything like that, but it's been a good spring for him."

The Eagles signed Jeffery in March to a one-year deal worth up to $14 million, hopeful that the accomplished receiver would give Wentz the No. 1 target he desperately lacked as a rookie. Free agency is always a bit of a crapshoot, but the Eagles had a valuable resource in Groh to take some of the guesswork out of the process.

During their first two years together in Chicago, Jeffery -- working opposite Brandon Marshall -- racked up 174 catches, over 2,500 yards and 17 TDs. His lone Pro Bowl appearance came in the '13 season that Groh referenced. Marshall made it that year as well. As a show of gratitude, the two receivers paid for Groh to join them in Honolulu.

"Well I think that says a lot about Alshon and Brandon that they would bring myself and Carson Walch, who was an assistant receivers coach that year, both of us out there to Hawaii as a celebration of the seasons that they had. That's what it's all about," he said. "We want to help them be as successful as they can as coaches and be the very best player they can be, and just for them to spend their own money to bring us out there says a lot about them. And I think just having that player-coach relationship, it's really a partnership, and trying to help him become the very best he can be, and if he can do that, we're going to have more success on offense."

Injuries began to creep into the picture in 2015, their last together in Chicago. Limited to just nine games, Jeffery finished with 54 catches for 807 yards. He has scored just six touchdowns over the last two seasons after piling up 20 over his first three campaigns. With Jeffery currently healthy and back together with his old coach, the hope is that he'll return to form in '17.

"He's competed at a high level," head coach Doug Pederson said earlier this offseason. "He's wanting to get better. He's taking the coaching from Coach Groh, who he knows, and he's showing really, I think, a little bit of the veteran experience and presence out there on the field. He's exciting to watch."