Boston's missing piece may be Detroit's Mike Green this deadline.

Don Sweeney, it appears, is playing his cards close to his chest this trade deadline.

With the trade frenzy seemingly beginning on Sunday night and continuing on Monday, the only sound from Boston was silence, or failing that, denial. Sweeney has already said the Bruins "probably" won't make a move before the clock ticks past the deadline on Wednesday, which has been greeted with a mixed response in New England.

On the one hand, the B's have only lost one game since Bruce Cassidy took over from Claude Julien, and are playing with a verve and speed not seen in these parts in a long time.

On the other, however, the small sample size of the Bruce Cassidy tenure so far and the knowledge that the B's can still ill-afford any slip whatsoever from a team that has swung between awesome and awful and back again on a regular basis this season, coupled with the well-publicised defensive issues from this team, mean that there is a nagging question as to what this team can do going forward.

Defensively, it needs a puck-driving d-man, which is why there's all the noise in Boston around Kevin Shattenkirk. As the top player out there at the deadline on the blue, it's probably inevitable that the Bruins are going to be linked with the former BU Terrier standout.

The price for Shattenkirk, however, is likely to be astronomical. Certainly more than the Bruins are willing to pay for a player this deadline who will then demand a long-term, highly expensive contract that will likely handcuff them for several years.

What the Bruins need, ideally, is a top-four offensive defenseman from a selling team who isn't likely to be hugely expensive to acquire, isn't a rental player but at the same time doesn't have a large amount of term on his contract. This mythical defenseman also needs to be one that's still got plenty of miles in the tank, can provide a genuine offensive threat and munch considerable minutes both at even strength and on the powerplay. Ideally it also needs to be a player whose current team is one they can exert a little leverage upon when it comes to trade negotiations.

That's a pretty specific set of requirements. One that would normally have GMs tearing their hair out looking, because it's not a situation you'd expect to come together very often.

Except this season, luckily for the Bruins, there is such a defenseman.

That defenseman is the Detroit Red Wings' Mike Green.

On the face of it, Green's contract, at $6 million a year for this season and next, looks a little steep, especially when one considers that it's also the price that Shattenkirk was reportedly asking in the deal that was turned down in Tampa Bay.

Green, at 31, is bang in the middle of his prime years as a defenseman, however, and has arguably hit the sweet spot between ability and experience. He's also a proven offensive player in the NHL (only the eighth defenseman ever to score 30 goals in a season), and in his prime one of the most feared blue-line weapons in the NHL.

Unlike Shattenkirk, too, he has a point to prove to any team that acquires him from the moment he arrives.

It is fair to say that the last few seasons for Green haven't quite hit the meteoric heights of his first few seasons with the Washington Capitals (including that 30 goals season and a truly monstrous 76 point season the year after before injuries hit). Indeed, after injuries between 2012 and 2015 there were questions over whether he would ever be close to the same player again.

However, with the Wings, he's led the blue-line in scoring both seasons even in supposedly "down" years (he's doing so right now, in fact).

Next year he'll only be aged 32, and - here's the key thing that should interest the Bruins - his contract expires.

So what the Bruins could have, potentially, is one of the best offensive defensemen in the league in his prime, in a contract year, looking to prove to all and sundry that he's still worth a big payday.

You think there's not potential for a seriously good one-year-investment, right there?

Unlike Shattenkirk, though, the Bruins would be able to be flexible with Green. With no long-term contract to be locked into, they're effectively taking him, for now, on a season trial basis. If he's superb, the option's there to re-sign him. If he isn't, or the Bruins need the cap-space elsewhere, they have far more flexibility than with a player only 3 years younger but locked into a monster contract. Flexibility to go out and grab another free agent next off-season, for example. In an NHL where cap flexibility is all, Green provides it in a way Shattenkirk does not, for fairly comparable potential reward.

But there's more. Whilst the Blues know that they have to sell Shattenkirk if at all possible this deadline for maximum reward or risk losing him, they have options. The Wings, hard up against the cap and in a transitional phase, would love to make themselves some cap space...cap space that the B's can most certainly provide.

Granted, this off-season the Bruins do have to re-sign David Pastrnak and Ryan Spooner, which will require a good chunk of cap space. However, with $17 million available currently and players like J-M Liles and Matt Beleskey available as potential trade pieces the other way, they can find ways to absorb Green's hit, for next season at least. Liles in particular going the other way provides the Wings with a stop-gap now and his UFA status this season allows for the full hit to come off the books come free agency.

The price the Wings are asking, too, is reasonable, at least if you look at our sister blog Winging It In Motown. That first, it has to be admitted, is not something the B's would probably want to give up, but let's say the Bruins offer a rebuilding Wings Jakub Zboril for the future, JM Liles to fill the gap for now, and a 2nd round pick in a weak-looking 2017 draft. Or, if Don Sweeney is going all-in for a playoff run, with the Wings looking for something, anything to back up their aging forwards, up the ante by throwing in names like Matt Beleskey along with Zboril. If they're REALLY serious, then Ryan Spooner can be thrown in, too.

The Bruins, then, are giving up a pending UFA, a prospect, and a pick, a middle-six forward who hasn't produced as they've hoped this season along with a prospect from a strong system, or at WORST another pending UFA forward who, while skilled and popular in Boston, is ultimately expendable, for an offensive defenseman who offers the same advantages of Kevin Shattenkirk but with the added flexibility of a relatively short contract.

Here's another argument - imagine Charlie McAvoy learning from Green, one of the pre-eminent offensive NHL defensemen of the past ten years. Is that a prospect that excites you? It should. Just as imagining the B's PP with the twin howitzers of Chara and Green lining up to blast away this season should instantly improve your mood.

There are of course downsides here. Green has an NTC, for one, which means that the Bruins would probably have to sell themselves to him as a destination - something that could be accomplished by basically saying that he's going to become the key man on the PP alongside Chara or (in future) Krug. He is also not necessarily the long-term solution.

But here's the thing - the Bruins aren't going to find a long-term solution through trades right now at this deadline. What Mike Green does is gives them options in the future, while instantly improving the team right now for the stretch run for a price that won't break the bank.

This trade deadline, Green for Go might just be the solution the Bruins never expected.