McCarthy has called the veteran a ''sneaky preparation guy'' for the time he quietly puts in behind the scenes.
It all pays off on Sundays.
Back with the Packers after a year away, Jones has made an immediate impact just more than a week after getting cut by other teams twice in four months. The two touchdown passes he caught from old friend and quarterback Aaron Rodgers in the season-opening win Sunday at Chicago made it seem as if Jones never left.
''He's a guy who has got a lot of grit. He digs down and he makes some contested plays,'' Rodgers said after practice Wednesday.
Jones went from the NFL discard pile to a go-to guy for the league's Most Valuable Player.
Sometimes, it works out quite nicely after getting cut.
''You have a lot of trust in a guy like that,'' Rodgers said. ''We're just excited we've got him back.''
The Packers signed Jones last week to fortify an injury-stricken receiving corps. Jones made a triumphant return to the team that drafted him in the third round in 2007.
Jones was cut by the Giants when final rosters were due on Sept. 5 after spending a month in New York's training camp. Playing in an offense coordinated by former Packers assistant Ben McAdoo, Jones led the team with 15 catches for 187 yards.
Not good enough.
The Giants went with fourth-year veteran Preston Parker, who played in all 16 games last season, including seven starts; and rookie Geremy Davis, a sixth-round pick who can provide a deep threat. Parker also has experience on special teams, which Jones doesn't play.
The Raiders signed Jones to a three-year contract in the 2014 offseason and he had a team-high 73 catches last season for 666 yards and six touchdowns.
Not good enough.
After that season's first three weeks, Jones played mainly in the slot, which he hadn't previously played with any regularity. The veteran turned into a security blanket of sorts for young Raiders quarterback Derek Carr.
Jones' 9.1 yards per catch was the second lowest of any receiver last season, leading the team to go in a different direction after drafting Amari Cooper and signing Michael Crabtree. Jones had been due $3.4 million this season, which was more than the Raiders wanted to pay for a player they slotted as a backup.
In Green Bay, there couldn't have been a better landing spot for Jones on such short notice.
''Man, I have a chip on my shoulder because I got released,'' he said. ''If they fired you, aren't you going to be mad?''
And Jones said that days before he had his big outing against the Bears. Now, it's as if Jones never left Lambeau after the 2013 season.
''It's home for him,'' Raiders wideout Rod Streater said. ''I'm sure he didn't miss a step, obviously, with two touchdowns. That's great to see.''
Cobb excels in the slot, so that position is covered. Nelson played primarily outside. Jones, with his years of experience with the Packers' offense, got a call.
To offensive coordinator Edgar Bennett, Jones' immediate impact was the result of all that extra work on the practice field and in the film room. Jones got together with Rodgers to go over any tweaks added to the system while the receiver was away.
Jones and Rodgers have also worked out together at times during previous offseasons, sessions that can always help build lasting connections between a quarterback and receiver.
''A lot of it has to do with chemistry with our quarterback, trust with our quarterback,'' Bennett said. ''It definitely paid off.''
AP Sports Writers Josh Dubow in Alameda, California, and Tom Canavan in East Rutherford, New Jersey contributed to this report.
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