Some days, the subway seems worse than ever.

Chunks of debris rained down on the platform at the Barclays Center stop in Brooklyn last week. Just days before, storms flooded stations and christened a new subway mascot: Flood Rat, a rodent spotted cowering behind a pillar as water surged around it.

But subway officials say the system is slowly getting better — if you look closely.

On Monday, Andy Byford, the leader charged with saving New York City’s subway, argued that the system is improving in a presentation to the Metropolitan Transportation Authority board.

“The statistics show that we are turning the corner where we need to turn it,” Mr. Byford said. “There is no panacea. You don’t just click your fingers and undo decades of underinvestment.”

But New Yorkers are frustrated that the subway is still unreliable more than a year after the agency began a roughly $800 million rescue plan to fix the system.