Mathieu Darche got a crucial piece of the puzzle out of the way on free agency eve, signing Alexander Romanov to an eight-year extension that, per a league source, will carry an average annual cap hit of $6.25 million. 

In this summer of offer sheets, Darche had to get much work done on the restricted free agency front before July 1. He ended up trading Noah Dobson to Montreal and handing Romanov a long-term extension to shore up the left side of a defense that now includes No. 1 pick Matthew Schaefer in its future. 

Simon Holmstrom, Max Tsyplakov, Emil Heineman and Marc Gatcomb remained unsigned, but once those deals get done, they should take up just under half of the Islanders’ remaining $15,473,334 in cap dollars, though Gatcomb is unlikely to start the season on the NHL roster. 

Ballpark it in the range of $9 million, give or take, remaining for Darche to play with while attempting to shore up a roster that needs help at right defense. The Islanders could use an additional scorer and an insurance policy on Semyon Varlamov’s knee in the form of another goaltender. 

In essence, Darche made a bet on Friday that the $9.5 million Dobson is getting paid annually by the Canadiens could be better spent improving the roster elsewhere. 

Now that Aaron Ekblad, the lone star righty defenseman set to enter unrestricted free agency, is reportedly staying in Florida on a team-friendly eight-year, $6.1 million deal, elsewhere might not mean spending money on a player to replace Dobson, but on another position entirely. 

The route to bringing back Tony DeAngelo looked closed off just a couple weeks ago. Now it appears wide open, as DeAngelo represents a low-cost offensive defenseman who plays the right side, can run the power play and eat minutes if necessary.

It’s not ideal if the plan is to put DeAngelo on the top pair again, but the Islanders’ best option in free agency appears to be taking what’s in front of them on defense, hoping the situation works itself out and spending their money elsewhere. 

There are plenty of options as far as how to do that. 

Darche would be spreading himself thin, and taking a win-now risk, by entering the Nikolaj Ehlers or Brock Boeser sweepstakes. Ehlers has been connected to the Islanders before, but while the Isles have money, they don’t have the money to enter a bidding war, especially for a winger who has never topped 64 points in a season. 

The more likely option looks like the Islanders spreading their money around between two or three mid-to-low cost options. If Darche plays his cards right, that could allow him more future flexibility, either at the trade deadline or next summer — both of which should be of more value to the Islanders than overspending now, with a not-great free agent class and a team that’s way more than one piece away from title contention. 

We saw at the draft, and with the acquisition of Emil Heineman, that Darche prizes compete level and physicality. 

“We just tried to get the same type of the compete level and the high character that I mentioned [Friday],” Darche told The Post Saturday. “These are the people that tend to overachieve.” 

He was speaking about the players the Islanders took on Day Two of the draft. The sentiment, though, is applicable to a free agent class that is light at the top but from which you could construct any number of strong bottom-six lines. 

Two of Heineman’s former teammates in Montreal, Christian Dvorak and Joel Armia, for example, fit that mold. So do Nick Cousins, Nick Bjugstad and Nate Bastian. 

The last contender that came out of Long Island was propelled in no small part by the bottom of the lineup. Darche might have an opportunity to do something similar here.