FOXBORO — Dion Lewis and Rex Burkhead rapidly have increased their value during the New England Patriots’ eight-game winning streak as the offense morphed into a running back-centric machine.

The pair of 27-year-olds can only hope that value remains in place in three months when they hit the most important free- agency period of their careers.

And that’s when the Patriots must assess the need to keep both, one or neither.

REX BURKHEAD

“We’ll see. I’m just really focused on the season right now,” Burkhead said. “Whenever all that stuff happens, it will just take care of itself.”

It seems like an obvious choice to keep them around but there are other factors to consider. First, the Patriots already have $162 million allocated toward the 2018 salary cap, the seventh- most in the NFL. The cap could rise to the $177 million to $180 million range.

The Patriots probably can free up about $5 million by extending Tom Brady’s contract and as much as $22.1 million, with potential cap casualties like tight ends Martellus Bennett ($6.4 million, if released) and Dwayne Allen ($5 million), defensive tackle Alan Branch ($3.7 million), linebackers Shea McClellin ($2.35 million) and David Harris ($2.25 million), and running back Mike Gillislee ($2.4 million).

All the while, the Patriots’ group of impending free agents includes left tackle Nate Solder, cornerback Malcolm Butler, slot receiver Danny Amendola, and special teamers Matthew Slater and Nate Ebner. Solder and Butler each would command a minimum of $10 million annually, and that’s a conservative estimate.

Also, Coach Bill Belichick makes an annual habit of juggling lesser-known running backs, which can be traced back to 2005 when Corey Dillon suffered an injury that derailed the offense. Since then, the Patriots’ yearly rushing leaders have included a wide range of players, from castoffs LeGarrette Blount and Sammy Morris, to undrafted sparkplugs BenJarvus Green-Ellis and Jonas Gray, to higher draft picks such as Laurence Maroney and Stevan Ridley.

Lewis and Burkhead fit a similar mold. Lewis arrived in 2015 on a future contract, which was a sign of his obscure status, but quickly proved his worth and signed a two-year, $3.4 million extension in October 2015. Burkhead was rescued from the bottom of the Bengals’ depth chart last offseason with a one-year, $3.15 million pact.

At this point, neither is closing in on a contract extension, according to sources. And considering it’s a rarity for players to land extensions in December – no one on the current roster signed deals in December with the exception of two promoted practice squadders – signs point to Lewis and Burkhead entering the offseason without a deal.

DION LEWIS

Lewis has led the Patriots in rushing each week of their win streak and has blown away his career highs with 112 carries, 590 yards and three touchdowns. Burkhead’s value has been in his versatility; he has 55 carries for 244 yards, 24 receptions for 204 yards and six touchdowns.

While James White is a pass-catching extraordinaire who can take a handoff and Lewis is a run-dominant back who can catch a pass here and there (15 grabs, 87 yards, touchdown), Burkhead forces defenses to consider everything, particularly on the goal line where he has scored rushing and receiving.

“It’s just been fun,” Burkhead said. “I don’t know why it’s been such a great fit, but I know I’m trying to fill the roles the coaches want me to and it’s great to be part of the team atmosphere. You have guys who come in every day with the mentality to get better and improve on last week, and it’s just a joy to be part of it.

“I know the skill set I have. Whenever I have the opportunities, I try to make the most of it. I think the coaches do a great job here of putting all of us in positions to succeed. When you have that, it makes your job a little easier. It’s definitely a fun offense to be a part of, and I’m just trying to make the most of it.”

For those reasons, Lewis would be within his right to ask for a contract in excess of Gillislee’s two-year, $6.4 million deal. Considering his age, Lewis probably wants the security of three years, maybe worth $10.5 million. Burkhead might eye a payday similar to White’s three-year, $12.7 million extension.

It was uncharacteristic last offseason for the Patriots to dole out contracts to running backs White, Gillislee and Burkhead that were in excess of $3 million annually, especially given their hard-line negotiations with Blount, and have yet to reap the benefits of the Gillislee deal. So would Belichick double down by extending both Lewis and Burkhead?

The Patriots undoubtedly will lose a few key contributors next offseason for contract reasons, but the emergence of Lewis and Burkhead has mitigated the pain of shortages elsewhere due to injuries and other circumstances.

It’s all part of a challenging equation Belichick must solve in three months.