On a New England Patriots team that currently sits atop the NFL heap as defending Super Bowl Champions, two star players stand out above the rest as cornerstones of the franchise.

Tom Brady is the Patriots’ long-time leader and face of the franchise, a veteran of 15-plus seasons and owner of four championship rings. The 38-year-old Brady is in the conversation for greatest quarterback of all time, regardless of the stains on his legacy from various scandals over the years. Tight end Rob Gronkowski is relatively new to this. At age 26 he is just entering his sixth NFL season, however his impact since arriving in New England is undeniable. He’s already accomplished enough in five NFL seasons to be considered one of the game’s best tight ends ever, even if he called it a career tomorrow.

Both men have established themselves among the league’s truly elite at their respective positions and as indispensable players for the Patriots. New England simply wouldn’t be where they are today, as reigning Super Bowl champion with an opportunity to defend that crown, without both Brady and Gronkowski.

But here at the start of the 2015 season, it’s valid to wonder which player is more essential to the Patriots? If one of them were to go down this Sunday, which loss would hurt less?

New England almost had to deal with this scenario as “Deflate-gate” raged on throughout the offseason, threatening to keep Brady off the field for the first four games of the season. But with a week left to go before the opener, Brady’s suspension was lifted and the Patriots celebrated NFL Kickoff last Thursday night with a big game from their fearless leader at quarterback and his hulking sidekick at tight end.

Brady and Gronkowski both starred in last Thursday’s 28-21 season-opening win for New England over the Pittsburgh Steelers. Brady completed 25 of his 32 pass attempts for 288 yards and four touchdowns, and Gronkowski hauled in five catches on eight targets for 94 yards and three touchdowns.

While Brady’s presence was vital, during Thursday’s game in particular it looked like Gronkowski was the more valuable of the two for New England. In addition to his five catches and three scores, Gronk also made one of the most heads up plays of the game when he pounced on the ball for a key fumble recovery after Dion Lewis coughed it up near the goal line early in the fourth quarter. Gronkowski caught his third touchdown of the game a few plays later. He was awarded the game ball by New England coach Bill Belichick and his performance made some begin to wonder whether Gronk, with his playmaking ability and the problems he causes for opposing defenses, had surpassed Brady in value to the Patriots.

“You’re talking about the best tight end in the league,” said Bills defensive tackle Kyle Williams, whose Buffalo team faces the Patriots this week. “He can run, he can block, he can catch the ball, run after the catch. He does a lot of dangerous things in the red zone. You can split him out and get him the ball. So he’s somebody you really have to account for on every given play, and you have to identify him and have to double him up when you can. But you also have to ask guys to hold up when you need bodies other places. So he’s a tough matchup for anybody and we have to be ready for it.”

The 6-foot-6, 265 pound tight end was an absolute matchup nightmare for the Steelers, showing on several occasions that no cornerback, safety, linebacker or defensive end on the Pittsburgh roster was capable of hanging with him. And Brady’s skill didn’t factor much into his success. Gronkowski’s first touchdown came on the type of throw that most professional quarterbacks can make. It was a quick pass to Gronk, who was lined up as an outside receiver, a position from which he bullied his way forward for a 19-yard touchdown. The other two scores came on red zone tosses that required some touch from Brady, but that Gronkowski hauled in mostly because of his size and strength. Patriots wide receiver Julian Edelman said after the game that Gronk looked like a schoolyard bully pushing around the Steelers all night.

“I’ve said it over and over, he’s just a beast,” Edelman told NFL Network. “It’s like watching, sometimes, an eighth grader play with second graders.”

Gronkowski’s three receiving touchdowns matched a career-high, one he had hit three times before. The Patriots won all four of those games. In fact, New England is 14-1 in games Gronk hauls in multiple touchdown passes, with just a loss against this coming week’s opponent — the Buffalo Bills — back in 2011 as the lone blemish on that record. Since his arrival in the league, the Patriots are 38-6 in games that he scores at least one touchdown, and 59-15 with Gronkowski in the lineup. Gronkowski has missed 18 games over his first five seasons, and New England is just 12-6 (66.7%) in those contests.

There’s no doubting that Gronkowski is one of the best players in the league right now and should be for the next several seasons barring injury. He’s really just entering his prime and has appeared unstoppable at times over the last year, since he got back to full strength from the knee injury he suffered in 2013. He’s been a hugely important part of what the Patriots have been able to do since, helping them reach and win the Super Bowl. He’ll likely present that type of value long after Brady has retired.

But as great as Gronkowski is, and as important as he is to what the Patriots do on offense, Brady is still the more valuable guy in New England, and will be until he decides to hang up his cleats.

To this point, all 74 games Gronkowski has played in his career have come with Brady under center, so the Pats don’t know a life with Gronk and not Brady. On the other hand, Brady played plenty before Gronk arrived in 2010 and has played all 18 of those games Gronkowski has missed the last five years as well. Brady’s career mark without Gronkowski is still 123-40 (.755), nearly the same as his overall record of 182-55 (.768) as a starter over his 15-plus seasons in the league.

Brady has missed just 15 games since taking over as New England’s starting quarterback in 2001 and leading them to a championship that season. All 15 of those games came during the 2008 season, when he suffered a season-ending knee injury in Week 1. The Patriots were 10-5 (.667) in the games he missed, and failed to make the postseason. It’s one of only two times New England has missed the playoffs in the Brady era, the other being his first full season in 2002.

While Gronkowski has always had one of the game’s best quarterbacks ever throwing him the football, over the last decade and a half, Brady has been surrounded by a cast of characters with varying degrees of talent, and still managed to keep the New England offense humming.

On the 2001-2006 Patriots, the leading receivers were the likes of Troy Brown, David Patten, Deion Branch, David Givens and Reche Caldwell and the only one who broke 1,000 yards receiving in a season was Brown, who had 1,199 yards in Brady’s first year starting. Still, over those first six seasons with Brady under center and those lead receivers, the Patriots made the playoffs five times. The production from the tight end position was even less prolific. In fact, only once in Brady’s first four years as a starter did a tight end break the 400-yard mark, and that was Daniel Graham with 409 yards in 2003. Nonetheless, the Pats won three Super Bowls in Brady’s first four years as the starter.

It wasn’t until 2007 that the Patriots started to supply Brady with some elite offensive firepower at wide receiver in Randy Moss and Wes Welker. It came even later at tight end, when the team drafted both Gronkowski and Aaron Hernandez in 2010.

But no matter the personnel, Tom has been terrific. Since his first full season as the starter in 2002, Brady has surpassed 3,500 yards passing every season except for his injury shortened 2008 campaign. He’s eclipsed 4,000 yards passing seven times and 5,000 once. He’s also led the league in passing yards twice, including once in 2005, when Branch, his top wideout, checked in with less than 1,000 yards receiving individually. That type of consistency and ability to raise the level of his teammates is what sets Brady apart from his peers at the quarterback position.

There’s no doubt that having Gronkowski creating matchup problems and offering one of the league’s most reliable targets has aided Brady’s success in his late 30s. Four of those seven 4,000+ yard seasons have come since Gronk came into the league. He’s become one of the best pass catchers in the game and a players team have to account for, and still can’t contain. That makes Brady’s job a whole lot easier.

However, because of what he’s been able to accomplish with other lesser players around him, it’s hard to believe Brady wouldn’t be able to adjust to life with Gronk if he were pressed into it. That adjustment and the absence of Brady’s best weapon would make it far less likely for the Patriots to contend for a Super Bowl. But it would be manageable, where the loss of Brady would be catastrophic to New England, regardless of the status of Gronkowski, who, while a great player, still needs a competent quarterback to get him the ball in spots to succeed as he does.

That’s why, despite the incredible production coming from his current favorite target Gronkowski, Tom Brady remains the Most Valuable Patriot.