Joe Whitt, Jr. possesses the greatest possible attribute for a DC reporting to Big Mac ... a demonstrated unquestioning fealty to Big Mac himself.
As for Whitt's performance as a DBs coach, it was, to be charitable, mixed at best.
He gets credit for helping to develop UDFA CBs Tramon Williams and (in 2010 rookie) Sam Shields who were two of the top three CBs when GB won the Super Bowl after the 2010 season -- the other CB was Charles Woodson.
Unfortunately, it was pretty much downhill after 2010.
GB's D finished 32nd in yards allowed in 2011 and never in the top 10 in points allowed for the rest of Whitt's time in GB (which ended after the 2018 season).
As for the CBs that Whitt coached specifically, Woodson got old and Casey Hayward was drafted to replace him. After being the 2012 defensive rookie of the year, he never did much in GB and was allowed to go to San Diego in 2016 on a cheap deal ... where he became an All-Pro.
For some reason, Whitt and the Pack's coaching staff also had Micah Hyde playing a slot corner position (the same Micah Hyde who snagged a key interception in the Cowboys' 2016 playoff loss to the Packers) when practically every Packer fan recognized his limited speed and great ball instincts were better suited to playing safety. Hyde, like Hayward, was allowed to walk in 2017, signed with Buffalo, switched to safety, and became an all-pro player.
FWIW, both Hayward & Hyde commented publicly about being miscast or misused in GB.
GB used its 1st and 2nd round picks in the 2015 on CBs Damarious Randall and Quentin Rollins and turned these young "talents" over to Whitt for development. Don't remember them? (Well Randall had a lucky Terrence Williams dropped pass to him pick 6 in the Cowboys 2017 loss to GB). Go ahead and google them, because only their close friends and families know much about their careers. Now, whether their lack of development is attributable to Whitt or the obviously declining skills of GB's then GM Ted Thompson is open for argument, but it is not exactly a ringing endorsement for Whitt.
Whitt became GB's passing game coordinator in 2018 (so had responsibility for safeties as well as CBs) and the season went so well that Big Mac lost his job and Whitt went with him.
For those looking for positives from his time in GB, it is certainly true that Whitt was quite young (he is only 42 currently) and he can hardly be blamed for having to report to Big Mac's longtime dinosaur of a Defensive Coordinator Dom Capers nor was it his fault that the GM Thompson kept using high picks on a bunch of loser DBs -- in addition to Randall and Rollins, GB spent its 2014 1st round pick on HaHa Clinton-Dix (remember him from last offseason) and its 2017 2nd round pick on Josh Jones (another former Cowboy -- seriously, look it up).
