MASSACHUSETTS - Daniel A. Grabauskas arrived at the MBTA as the guy who could fix the unfixable.

He had transformed the state's Registry of Motor Vehicles, a pit that held drivers virtually hostage for two or three hours when they renewed their licenses, into a place with Wal-Mart-style greeters at the door, a modern computer system, and 15-minute waiting times.

But three years later, the Massachusetts Bay Transportation Authority is far from fixed, and there are more political darts aimed at Grabauskas. He has earned praise from transportation activists for putting a focus on efficiency and access and has instituted customer service improvements such as the automated CharlieCard and the beginning of cellphone service on subways. But overwhelming debt, political infighting, and a recent series of controversies and crises at the T have tarnished his image.

In May, a trolley operator was killed in a jolting Green Line crash that highlighted the old equipment's susceptibility to human error. Soon after, Grabauskas fended off criticism for letting employees drive home state cars. This month, a federal lawsuit against a group of MIT students exposed how the T's electronic fare tickets could be reprogrammed to give free rides, leading one of the T's board members to say she had "lost all confidence" in the ability of Grabauskas to manage the agency.

"We're moving the ball in the right direction," he said. "But in this particular job, there is no end zone. You're either moving in the right direction, or you're moving in the wrong direction."

His team provided reams of lists and graphics, including a monthly system accountability book he initiated, to show where he is improving service and saving money. Canceled trips on buses and subways are down, and the fleets are running longer without breaking down, with fewer speed restrictions. Commuter rail, however, continues to run late more often than promised.