Sure, the 76ers want to move their home court from the arid asphalt desert that is the South Philadelphia sports complex, to the verdant edge of the Delaware River. But calling the team’s vision for Penn’s Landing an arena proposal is like saying Joel Embiid makes his living tossing around big orange balls.

What the billionaire owners of Philadelphia’s basketball franchise are really aiming at is something much bigger: development rights for a mile-long stretch of the Delaware waterfront.

The Sixers are one of several real estate groups that have recently submitted development proposals to the agency that oversees the waterfront. Ever since the city completed a master plan in 2010 to guide new construction along the river, that agency, the Delaware River Waterfront Corp. (DRWC), has been laying the groundwork for transforming the once-industrial landscape into a dense neighborhood of apartments and attractions. It has built parks on old ship piers, softened the wide expanse of Columbus Boulevard with new bike lanes, improvised beer gardens at Spruce Harbor Park and Cherry Street Pier, and started work on a $225 million cap over I-95.

All the while, the DRWC has been singularly focused on the big prize: the 13 acres of landfill created for the Bicentennial in 1976 and dubbed Penn’s Landing. Last October, it finally announced it was seeking development proposals for the site.

The waterfront corporation won’t say how many developers have responded, but we do know that the agency is getting close to picking a winner. DRWC president Joseph Forkin told me the agency expects to make an announcement by the end of September. The details that have been leaked about the Sixers’ proposal give us some insights into what other developers are thinking.

I have not seen any images from the Sixers’ plan, but it was described to me in detail by a source familiar with the proposal. In some respects, their scheme hearkens back to the bad days of the ’90s, when Mayor Ed Rendell was convinced that windowless destinations like shopping malls and casinos would soon transform the underpopulated Delaware into a Philadelphia version of Baltimore’s Inner Harbor. It is more than a little ironic that the Sixers are talking about erecting an arena — another windowless box — on Penn’s Landing at the very moment that DRWC is dismantling the massive concrete monolith that has stood there for almost two decades. Built in 2002 as the terminus for a waterfront tram that was never realized, that $16 million structure was an apt monument to all of Penn’s Landing’s failed development schemes.

And yet the Sixers’ plan also shows how much has changed since the Rendell era. The arena is a small piece of the project. Rather than pack Penn’s Landing with entertainment boxes, the franchise’s wealthy owners Josh Harris and David Blitzer are focused on creating a mixed-use neighborhood that is largely attuned to the spirit of the 2010 master plan. The proposal was even prepared by the planning consultant that cowrote the waterfront master plan, Cooper Robertson. In their submission to the DRWC, the Sixers promise to bring thousands of apartments, a hotel, two museums, a dozen or so restaurants, a supermarket, and a new public school — along with that 19,000-seat arena — to the Delaware waterfront. Some parking is envisioned, but most would be tucked out of sight.

Depending on how you feel about a bunch of sports executives taking on Philadelphia’s most cursed real estate project, the Sixers’ proposal is either a display of canny ambition or ill-informed greed.

The plan, according to the source who described it, “dwarfs everything anyone else has proposed.” While the DRWC competition document identifies two parcels for development — a 7.5-acre surface lot at Market Street and a 3.4-acre site just south of Spruce Harbor Park, near the marina basin — Harris and Blitzer have asked the waterfront agency to let them develop a much larger geographic area. Rather than limit themselves to the two sites, they want the rights to every riverfront lot between Market and Lombard. Having that extra land would allow the Sixers to build six residential buildings, instead of four — plus a hotel, offices, and school.

It’s no accident the DRWC competition started out with just two sites. Those parcels are located close to the new I-95 cap, which will eventually become the foundation for a lush green park. By populating the area north and south of that park, the DRWC was hoping to establish a core population to use and care for the space, and act as eyes on the street, making visitors feel safe.

Apart from the inclusion of the arena near Market Street, the Sixers’ proposal adheres to that approach. The team would build two towers immediately south of the Market Street arena, and two mid-rise apartment buildings on the marina site. All would have retail or restaurants on the ground floor. The marina buildings would also house new versions of the Independence Seaport Museum and Philadelphia’s African American History Museum. (The latter was conceived after a conversation with Mayor Jim Kenney, according to the source familiar with the Sixers’ plan.)

But Harris and Blitzer don’t stop there. Their plan would demolish the existing Seaport Museum — an awful box — and replace it with an apartment tower. They would also add several floors of apartments above the parking garage that serves the Hilton Hotel at Spruce Street.

Both are good ideas that the DRWC should run with, whoever wins the development competition. Replacing the Seaport Museum with apartments would give the new cap park a much-needed southern edge. But instead of merely adding a few floors to the Hilton garage, which presents a brutal face to Columbus Boulevard, why not just get rid of it and build a more street-friendly apartment-parking hybrid?

The Sixers’ owners have also set their sights on acquiring a long, skinny parking lot just north of the I-95 on-ramp, between Naudain and Monroe Streets. An existing pedestrian bridge that dead-ends in the parking lot would be extended to the river, integrating the forlorn parcel into the rest of Penn’s Landing. Harris and Blitzer would use that site to build a public school for the new Penn’s Landing neighborhood. It could also accommodate another apartment building and a medical office building, the proposal suggests.

By now you must be asking yourself how the Sixers’ desire for a new arena morphed into a such massive real estate project. The Sixers are currently tenants in the Wells Fargo Center, with a lease that goes until 2031. Why go to the trouble of building all this stuff?

The answer is that sporting venues are no longer merely places where you go to watch athletes perform; they’re the equivalent of a department store anchor in a shopping mall. As tenants in the Wells Fargo Center, the Sixers attract customers and generate revenue for the center’s owner, Comcast Spectacor, explained Rodney Fort, an expert in the business of sports at the University of Michigan. Why should Harris and Blitzer make money for someone else? Across the country, teams like the Golden State Warriors and the Detroit Pistons have developed new arenas as centerpieces of real estate developments. “Owning a sports franchise is now all about how it fits into a larger, wealth-generating portfolio,” Fort said.

It’s easy to understand what the Sixers get out of having an arena on Penn’s Landing, but not so easy to understand what Philadelphia gains. A big, windowless box won’t make the riverfront a nicer place to stroll or picnic. And do people really want to live in apartments next to an attraction that disgorges 20,000 excited fans on game nights? If Philadelphia were going to relocate one of the city’s windowless arenas from the sports complex, why not put it at Eighth and Market, a huge empty lot that happens to have some of the best transit connections in the region? Not a single new parking space would be necessary.

There are other reasons to be skeptical of the Sixers’ intentions. According to their plan, the arena will be one of the last pieces to be constructed. Are Harris and Blitzer going to stick around to see their plan through — or will they flip the Penn’s Landing project once they have the tax abatement they are seeking? Are Harris and Blitzer really the right people to further the master plan’s goal of making the waterfront inclusive and accessible to all, including people who come merely to enjoy the river breezes, not spend money?

In a statement, the DRWC said the winning proposal would be “consistent” with the master plan, a document that is the product of lengthy public process, involving hundreds of Philadelphia residents. Let’s hope the agency keeps its word. Since Penn’s Landing was created in 1976, at least a dozen development fantasies for the site have crashed on the shoals of reality. Philadelphia doesn’t need its waterfront to sit empty for another decade.