There is a fine line between talking tough and actually doing something catastrophically rash and stupid. And if the Baker Administration was to carry through on its threats to cancel the Green Line extension, make no mistake, it would be both catastrophic and stupid.

In one fell swoop, it would undermine billions of dollars in potential new development, from Lechmere to Union Square in Somerville and College Avenue in Medford, rivaled only by the boom unleashed by the extension of the Red Line through Cambridge three decades ago.

Yes, the MBTA’s hefty overrun on the Green Line extension is bad news, as well as more evidence that Gov. Charlie Baker is on the right track in his campaign to whip one of the most maddeningly dysfunctional government bodies ever created into some sort of reasonable shape.

But if at the end of the day, the state has to cough up another $73 million – the current budget gap after a series of deep cuts to the project – then so be it. Better that than allow another case of epic T incompetence to derail not only a badly needed new extension of our public transit system, but a development boom that would more than pay for itself through the new development, taxes, jobs and housing it will spark.

Tough Talk Good – To A Point

As things stand now, Stephanie Pollack, our hard-as-nails environmental secretary, announced just last week that the project will tentatively move forward.

As a rising young attorney at the Conservation Law Foundation, Pollack played a key role in holding up the permitting of the multibillion-dollar Fan Pier project a decade and a half ago. She helped get more parkland near the water, but it would take nearly a decade longer – and another developer – to get the project off the ground. Let’s just say Pollack knows how to play a little hard ball – and be the spoiler – if needs be.

Pollack and state transportation officials are reserving the right to put the kibosh on the whole thing if the budget for the Green Line extension goes bonkers again.

The project ran aground last summer after revelations that then-$2 billion project might instead cost another billion, raising the price tag to $3 billion for the extension, which would add seven new stops.

State officials last week averted the potential for an immediate shutdown of the project, approving a revised $2.3 billion budget that features bare-bones stations and scaled back amenities.

Armed with the threat of shutting the whole thing down, Pollack has also forced Cambridge and Somerville to cough up an extra $73 million, while the Metropolitan Area Planning Council will chip in more than $150 million that had been reserved for a later stage of the project.

OK, this is all fine and well – even masterful – on Pollack’s part, at least up to this point. The MBTA needs a harsh taskmaster and richly deserves every kick in the rear it is getting.

But instead of declaring victory, Pollack continues to threaten to cancel the project. There is still a remaining $73 million gap in the project that could wind up killing it, Pollack contends. In addition, if the costs go up, state transportation officials say they reserve the right to shut the whole thing down.

Cost Benefit Analysis Needed

Now here’s where getting tough ends and just being tragically short-sighted – or less nicely, pigheaded – begins. Maybe Pollack’s just keeping the heat on – probably not a bad thing, given the T’s ability to screw up a one-car parade. But let’s do a simple cost-benefit analysis here.

Ponying up an extra $73 million saves a project that is already on track to generate billions in new development, millions in new tax revenue, and likely thousands of new condominiums and apartments as well.

Developers around just one of the stops planned on the Green Line extension – Union Square – are pushing plans for a $1 billion remake of several city blocks around the station totaling 2.3 million square feet in residential, retail and commercial space.

The Union Square boomlet alone will yield more than 17,000 new jobs and 3,600 new apartments and condos by 2030, Somerville officials have estimated.

Property values in the neighborhoods along the Green Line in Somerville are expected to soar 16 to 25 percent, the Metropolitan Area Planning Council has projected.

All told, there could be another 6,000 apartments, homes and condos built in Somerville over the next several years, with as many as 1,200 affordable units, if city officials have their way.

Nor is the Green Line extension development boom limited to Somerville. The extension will also help provide a boost to the giant NorthPoint city-within-a-city development taking shape in Cambridge, where several million square feet of apartments, condos, labs, stores, shops, restaurants and offices are planned.

Frankly, even if the overrun ends up being a few hundred million extra – not just $75 million – the extension would still probably be worth it, especially after you factor the huge environmental benefits of more commuters on trains instead of cars.

So by now, you’ve either gotten the point or I’ve lost you completely. Let’s hope Pollack and the Baker Administration get it as well.

Crack away with the whip when it comes to the T, but don’t lose site of the bigger picture here. Don’t make us all suffer – and kill a huge development boom in the process – for the sins of the MBTA.