Arsenal got off to a winning start to the new Premier League campaign thanks to late goals from Aaron Ramsey and Olivier Giroud.
Speaking on 'Sky Sports', Henry said, "You can talk about evolution or revolution at Arsenal, I call it stagnation."
"I watched the game against Leicester and I could tell you what was going to happen.
"Every time Leicester had the ball I felt they were going to score and every time we had the ball I felt we were going to score.
"What I saw, I have seen so many times. Arsenal came back into the game, Aaron Ramsey came on and Olivier Giroud saved the day. But I have seen that too many times.
"Are you always going to score four and concede three? At some point you will be found out.
Henry believes Arsenal's defensive frailties is a major concern and may prevent the club from mounting a title challenge this season, or worse, returning to the Champions League.
"You expect Arsenal to control the game a bit more," he added. "It's not always easy in the Premier League but Tottenham didn't concede, Manchester United didn't concede.
"Usually you win titles because you don't concede goals. Yes, you score goals and we know Arsenal will score, but you need to be able to not concede. That is something Arsenal need to rectify.
"It's not only the back three, you cannot have your two holding midfielders bombing forward. At times they will score but most of the time you want them to do their job.
"I believe that team can compete but do they believe they can compete? That's very key, that's the first step, believing you can do it.
"Arsenal can make top four, I'm not convinced but I think they can. The problem in our league is a lot of teams can make top four."