Johnson, who now plays for Norwich City, displayed his talents against Wednesday, scoring twice in a 2-0 win last weekend, and Gray believes his team need to learn from that performance.
The Owls boss wants his team to pose a greater goalscoring threat next season and he would like some of his midfielders to start getting on the scoresheet as regularly as Johnson.
“I know Bradley Johnson because I have worked with him before and I spoke to him after the Norwich game," he said. "He came to wish me all the best for the rest of the season. I asked him how many goals he’s got and he said that’s 13 and he’s a midfield player.
“That (goals) is an area where we have fallen down short a little bit. When we have been on top in games, you’ve got to score and take your chances but we haven’t done that enough."
Wednesday have struggled for goals all season and it is an obvious area that they need to improve if they are to mount a promotion challenge next term.
The Yorkshire outfit have scored just 37 times in their 41 matches to date this season and unless they start posing more of an attacking threat then it is hard to see them breaking away from the mid-table spot they are currently in.
Wednesday do have some goalscoring midfielders - with Lewis McGugan a particularly notable player in this regard - but nobody in their squad has been able to match former Leeds man Johnson's total of 13.
At the moment Atdhe Nuhiu and Stevie May lead the club's goalscoring charts, but the two strikers only have seven league goals to their names this season and it is likely that Gray will be on the lookout for a new front-man in the summer.