You can make the case pretty darn easily the Rangers would have more trouble replacing Dan Girardi than anyone on their team.

Losing Ryan McDonagh would represent a huge blow, but Marc Staal could move up and assume the first-pair minutes and assignments on the left side.

The right side, where Girardi plays, is a different story. Anton Stralman, or yes, Michael Del Zotto, would be in line to assume the responsibility of being the Rangers’ match-up, shutdown guy on that side of the ice.

And it’s not that Girardi just plays; he plays and plays and plays, having logged the fifth-most minutes in the NHL since the start of the 2010-11 season, trailing only Ryan Suter, Jay Bouwmeester, Shea Weber and Duncan Keith, and yes, the impending unrestricted free agent’s reps at Newport Sports are welcome to send me a percentage for having written a bullet point or two of their contract negotiation presentation.

But here’s the conundrum regarding Girardi. If he is that valuable to the Rangers, who enter Monday’s match at the Garden against the Blue Jackets having won fewer than half their games (21-20-2), how valuable might he be as a rental to legitimate Stanley Cup contenders such as Boston, Anaheim, Los Angeles and San Jose?

Thus, how much more value as a trade chip, rather than as a first-pair defenseman, might Girardi bring to a Ranger organization that doesn’t appear close to a championship and all but certainly will have to undertake a significant reload over the next offseason or two?

It is, of course, impossible to answer the question blindly. Which means it is therefore incumbent for general manager Glen Sather to be in position to know with the March 5 trade deadline now less than two months away.

Sather must perform his due diligence and be aggressive about it. Girardi, who doesn’t turn 30 until late April, is as high-end a rental property as has gone on the market since Ilya Kovalchuk in 2010, if not Marian Hossa in 2008. The Rangers have every right — and every obligation — to demand a package of two “A” prospects, maybe already in the NHL or maybe not, plus a draft pick in return for Girardi.

Everyone assumes the Bruins, who lost Dennis Seidenberg to a season-ending knee injury in late December, will put in a call on Girardi. They haven’t yet. But there’s no reason why Sather (or, alternately, assistant GM Jeff Gorton) shouldn’t call Boston’s Peter Chiarelli to give him first crack at Girardi if the price is right.

What would the price be? No less than whomever the Rangers’ staff has identified as the Bruins’ top prospect up front and one of their two top prospects on defense, plus a draft choice.

Next for Sather: calls to the Ducks and Kings and Sharks. Same deal. One-time offer with the price liable to increase as the deadline approaches, buyers become bolder and available cap space expands.

What’s more, Sather must take exactly the same approach with Ryan Callahan, who too is a heart-and-soul guy but also is an impending unrestricted free agent and is likely to be a more expensive and more challenging signing than Girardi.

What would it be worth, for instance, to the Penguins or Blues to have Callahan, who turns 29 in late March, in a top-six role down the homestretch?

This is the hypothetical Sather must be prepared to address: Would the Rangers be closer to the Stanley Cup with Girardi and Callahan signed to long-term contracts or with the four high-end prospects obtained in their places through lend-lease?

Losing either, or both, would represent an immediate step back, of that there is no doubt. But it is always worthwhile to take one step back in order to take two or three steps forward.

And it is far, far more worthwhile than standing in place, which for years generally has been somewhere between sixth and ninth in the East.

Defenseman Conor Allen, scratched on Saturday in Toronto after having played three games since his Dec. 28 recall from the AHL, was returned to the Wolf Pack.