New England Patriots tight end Rob Gronkowski is tackled by Tennessee Titans safety Kevin Byard, rear, after catching a pass during an NFL divisional playoff game earlier this month in Foxborough, Mass. (AP Photo/Charles Krupa)

Late last Saturday night, Rob Gronkowski paced across the New England locker room, dressed in all black, decked in a coat with a fur-rimmed hood that was better suited for an arctic expedition than a news conference.

He walked alone, past teammates surrounded by reporters and preparing to leave for the night. He answered a few questions — it felt “super great” to be back in the playoffs — and then headed out himself, a rote conclusion to Gronkowski’s role in another Patriots postseason victory.

Nothing about Gronkowski, though — neither his presence, nor his performance — should be taken for granted. The contrast between the Patriots’ Tom Brady and the other three quarterbacks who will play in the NFL’s conference title games Sunday has been the dominant storyline this week. But the best and most important player remaining may be Gronkowski, the 28-year-old tight end whose availability enables Brady’s greatness.

The Patriots won the Super Bowl last year without Gronkowski, who missed the last half of the season after undergoing the third back surgery of his career. He returned to full health this season as New England used him carefully and he worked out with Alex Guerrero, the nontraditional trainer/guru made famous by Brady.

In the divisional round against the Tennessee Titans, Gronkowski caught six passes for 81 yards and a touchdown, giving him at least one touchdown in six consecutive playoff games. Gronkowski lined up everywhere — as a traditional in-line tight end, in the slot, out wide, even as a fullback before motioning down the line. The Titans tried to cover him with a multitude of players, in a variety of ways. None worked.

The challenge of stopping Gronkowski now flips to the Jacksonville Jaguars, who have better personnel than Tennessee. Linebackers Telvin Smith, Dante Fowler Jr. and Myles Jack have uncommon size-and-speed profiles — particularly Jack, who intercepted the Pittsburgh Steelers’ Ben Roethlisberger last weekend. But none can match Gronkowski’s 6-foot-6, 265-pound body.

Asked how the Jaguars could defend Gronkowski, Jacksonville coach Doug Marrone replied: “I don’t know if you can.” He cited Gronkowski’s size and speed, of course, but also his “catch radius,” meaning the area in which Gronkowski can snag a pass. His sure hands and long arms allow Brady an enormous range of possibilities to find an opening.

Gronkowski’s touchdown Saturday night provided the latest illustration.

With New England at the Titans’ 5-yard line, Gronkowski lined up tight to the right side of the formation, with safety Kevin Byard over him. Brady identified the Titans would be playing man-to-man defense. Gronkowski simply fluttered his feet, rammed into Byard, turned inside and spun all the way around to catch Brady’s pass, thrown outside. Byard was a gnat on an elephant’s back.

Brady had thrown the pass “where only Rob can get it and maybe only Rob could have caught it,” coach Bill Belichick said. “But Tom put it where Rob could get it, and Rob got it. So, like I said, two great players making a great play.”

On many of Gronkowski’s catches, he appears to be covered until the ball arrives, placed perfectly by Brady and allowing Gronkowski to wall off the defender with his massive frame. That’s the problem with trying to stop Gronkowski: Even when he’s well-defended, he’s open.

“That starts out in practice,” Gronkowski said. “I’m covered sometimes in practice. It builds up the trust in practice. Tom throws me a pass when I’m covered and just try to get open. He puts it where he can so I can get the ball. Just overall, you’ve got to expect the ball at any time as a pass catcher and running on routes. You’ve got to be ready at all times.”

Brady has a crowd of receiving options, including running backs Dion Lewis and James White, speedy wide receiver Brandin Cooks, reliable slot receiver Danny Amendola and deep threat Chris Hogan. And the Patriots managed to win a title last year with Gronkowski sidelined. But this season has placed Gronkowski’s importance to Brady in stark relief.

The Patriots scored at least 21 points in every game this season except two — the two games Gronkowski didn’t play: a Week 5, 19-14 victory over Tampa Bay that he sat out with a minor injury, and a Week 14, 27-20 loss to Miami that he missed because of a suspension. Against Miami, the Dolphins could play Brady’s outside receivers especially tight because they didn’t need to devote an extra safety to Gronkowski.

ESPN Stats & Info tracks the distance of every pass thrown in the NFL. With Gronkowski off the field this season through Week 15, Brady’s average pass sailed 7.4 yards in the air. With him on the field, Brady’s throws averaged 9.4 yards in the air. Gronkowski sucks in extra defenders, which often means there’s no safety to help on outside receivers running deep. And Brady is also more confident throwing deep to Gronkowski.

In the final five games of the regular season, Brady played through an Achilles ailment and struggled with deep passes. But Gronkowski was a salve. When Brady threw a pass at least 20 yards in the air to a receiver other than Gronkowski during that stretch, he completed 4 of 20. When throwing passes of that length to Gronkowski, Brady completed 5 of 6, many of them on seam routes, the pattern Brady is best at throwing.

“When you’re in one-on-one situations, there’s no better tight end in the NFL,” Patriots safety Devin McCourty said. “And I think everybody on the field knows that.”

For all of Brady’s brilliance, nobody makes a bigger difference than Gronkowski. At this time last season, the Patriots didn’t have him. Now that they do, he might be the best player left standing.