In his last days as New York City's Mayor, Michael Bloomberg seems determined to focus the media's attention on his administration's accomplishments and his own legacy. While the impulse at spin control is understandable, I think the effort is unnecessary. Bloomberg will be remembered as one of New York City's greatest mayors. Like his fellow three term mayors: LaGuardia, Wagner and Koch- his third term was not his strongest one. But I think his accomplishments are undeniable, and most New Yorkers know that he has been a great mayor.

I have often written about the high quality of New York's mayors and my clear sense that New Yorkers seem to have a gift for picking leaders appropriate to the time they govern. I think this was particularly true of Mayor Bloomberg. In his twelve years in office this city has faced three profound challenges. The first was the physical and psychological recovery from the terrorist attack on the World Trade Center. Bloomberg's steady and business-like approach set the correct tone after the heroic determination demonstrated by Mayor Rudy Giuliani in the weeks after the attack.

The second challenge was the financial meltdown and Great Recession of 2008-2009. A mayor with roots in the finance community, and a focus on sustainable economic development provided confidence that the city's economy would recover despite the damage to Wall Street.

The third challenge was Hurricane Sandy, the worst storm that New York City has endured in modern history. Superb first response helped keep people from harm's way and saved lives. An inspired $20 billion resiliency plan communicated that New York had a future and could rebuild strong enough to withstand the impacts of climate change. Bloomberg projected managerial competence and steady, consistent and confident leadership during each of these crises- and that was precisely what New Yorkers needed.

Still, running America's largest local government requires more than crisis management; it requires systems that lead to gradual change and steady progress in routine service delivery. Many of New York City's agencies demonstrated quiet, gradual service improvements during the Bloomberg years. However, no government is perfect, and Bloomberg's record on education was mixed and his team's approach to homelessness failed. His ability to communicate with the public improved, but it was never his greatest strength as mayor. Bloomberg's excellence was rooted in his ability to develop a data-driven strategy and then stick to it no matter how much opposition he faced. The down side of his determined and principle-based management was an occasional tin ear when a symbolic gesture or two could have placated opponents with little cost.

A number of retrospectives have already discussed the physical transformation of the city over the past decade: the glass-skinned towers, increased park land, improved playgrounds, Bike Lanes, the High Line, the street furniture in Times Square, the revitalization of downtown Brooklyn and Long Island City. Incredibly, public safety continued to improve throughout his tenure, and the NYPD developed one of the world's most sophisticated anti-terror units. PLANYC 2030's sustainability initiatives helped reduce New York's pollution while increasing its livability and energy efficiency. Capital projects like the third water tunnel and the extension of the number 7 subway line to the far west side are signal accomplishments of the mayor and his team.

While Mike Bloomberg was the right mayor for his time, that time is drawing to a close. My guess is that this recent public relations campaign stems from his concern that his term as Mayor will be defined by his successor just as Rudy Giuliani defined David Dinkins' time in office. Rudy and his followers distorted Dinkins' record and Mayor Dinkins' response was never as effective as Rudy's attack. While that could happen, Bloomberg's longer term of office, along with his wealth, media empire and continued public role should ensure that his impressive record will not be forgotten.

With the economic status of the city reinforced and its role as a global capital reclaimed, New York is strong enough to reassert a traditional role that had to be deferred over the past several decades: providing help and opportunity to those in need. While New York certainly retained a stronger social safety net then the rest of the United States, in recent years our progress has been halted. As global cities began to compete for highly mobile brain-based businesses, our ability to generate new revenues ended. New York City's education, health and social service systems require creative new approaches, but have been too inflexible to respond to the challenges they faced.

Bill de Blasio's election should not be seen as a rejection of Mike Bloomberg's accomplishments, but as an indication that the city is confident enough to focus on its embattled middle and working class residents. The financial strength of the city is gentrifying traditional middle class neighborhoods- from Astoria to Inwood. The absence of federal housing funds has created a maintenance crisis for the homes of 400,000 New Yorkers living in public housing. The growth of homeless families along with and an inadequate supply of affordable housing are all part of the tale of two cities told by Bill de Blasio.

There were a number of other signs that a more self-confident city was ready for a different type of mayor and different approach to policy. While no one wants to see an increase in violent (or any other) crime, the controversy over stop and frisk demonstrated that the public was ready for a less aggressive approach to crime fighting. The popularity of de Blasio's proposal to tax the rich to fund universal pre-kindergarten programs is another indication that we no longer fear a massive outflow of the city's wealthy residents along with the businesses they run.

So the times have changed, and so have our elected officials. Despite this slight change in tone, anyone looking closely at New York's government knows that most of the changes put in place over the past dozen years are here to stay. The new mayor's appointments for Police Commissioner and First Deputy Mayor are seasoned veterans known for their competence. I suspect that many of de Blasio's appointments will look a lot like these first two. As Fiorello La Guardia once famously observed, "there is no Democratic or Republican way to pick up the garbage". The work of local government is largely the delivery of routine but essential services. Every mayor knows this, and if they forget, New Yorkers are not shy about reminding them that school buses, snow removal, trash pick up and safe streets are not optional, but required.

Ironically, the many accomplishments of Mayor Bloomberg and his team may have made de Blasio's election possible. The voters felt confident enough about the health of the city to reject continuity and opt for change. I believe this was an implicit recognition that the New York City of 2013 is not the same city we experienced in 2001. The growth, sustainability, economic development, and renewed swagger of today's city are the heart of Mike Bloomberg's legacy. Think back to January 1, 2002: None of us were confident that we would ever "get back to where we once belonged". But we have. New Yorkers may never love Mike Bloomberg, but they ought to thank him for his dedication to public service and for the city he did so much to rebuild. I am certainly grateful for what he has done, but like many New Yorkers I am also looking forward to the more community based governance I think we are likely to see under a Mayor de Blasio. Bloomberg's legacy is the revival of a great and special city; de Blasio's promise is the possibility that more New Yorkers will enjoy the benefits of the city's comeback. Different mayors for different times.