Actually quite a few of a WR’s are on the jugs machine after practice & run routes with the QB’s.
They even did it last year too, Perry used to stayed for a hour-two hours after practice throwing to multiple WR’s, Pope & Wiggs included.
The issue is not that they don’t work on their ability to catch the ball, they’re just not that good at it, because they either lose focus & confidence in game, or they just get physically taken out of a game because they can’t deal with heavy press man bump & run pressure.
Wiggs would get physically beat up by the Corner covering him & he would retreat back into his Turtle shell for the rest of the game, he also isn’t a very adept route runner as is, so once a CB see’s that Wiggs can’t deal with the physicality he’s finished because he’s gonna be all up in his sh*t all game long playing Press man. It’s simply a one on one matchup at that point & in that arena Wiggs doesn't have the mental or physical toughness to deal with it, despite being 6’3 195lbs with 4.4 speed.