Stockdale signed for the Foxes on-loan last week and Flowers said: "We had a good look at him but Fulham killed us off when they came in for him.
"He's been a lucky lad at Fulham because he is with Mike Kelly, who I think is the best goalkeeping coach in the business.
"I worked with him when I was at Southampton and I went from being a run-of-the-mill keeper to being fortunate enough to play for England.
"I saw David the other night and he looked in good shape. He's a bit more toned out. Fulham are keeping him very sharp, although he's not getting games.
"He will benefit from going to Leicester and playing matches."