The winger completed a £3.75m move to Premier League high-flyers Leicester City.
The 19-year-old completed his switch to the Premier League high-flyers yesterday, and with £3.75m being paid to the St Andrew's outfit (via Mail), Gleeson is backing Gary Rowett's men to become stronger despite losing their brightest prospect. However, he also warned the club's hierarchy that failure to make any signings could have a very negative impact.
"With Dimmy going we can bring in players and add strength to the squad. It could make us stronger," he explained to the Mail.
"It's going to be a massive loss to us but hopefully the management team can have two or three weeks to add to the squad, if not with one then probably two wingers and four or five overall.
"If we can add it could make us stronger, but if we don't it will definitely weaken us."
While in the long-run Birmingham are likely to be disappointed to have lost Gray, the funds they have received will probably aid their promotion cause for this season more than perhaps Gray would.
The youngster was unquestionably one of the most exciting talents that were plying their trade in the Championship during the first-half of the season. However, it is safe to say that his talent was too raw for him to be relied upon to drive the Blues into the promotion picture.
He scored just once and bagged one assist, and with the club needing to make up some ground if they still wish to make the play-offs, Rowett may now be able to reinvest the money made from Gray's departure on an established player that is able to help the club bridge the gap to Ipswich in sixth.