Rob Gronkowski will make contract statement by missing Monday’s practice

The Patriots will hold their first practice of the 2018 season on Monday, and neither their star quarterback nor tight end will be in attendance. But Tom Brady has a valid excuse. Rob Gronkowski is simply upset, and making his displeasure known.

Gronkowski won’t be present today at Monday’s voluntary workout, per ESPN. Gronkowski, set to make between $8 milliom-$9 million this season, wants a pay raise, and has been openly contemplating retirement since shortly after the Patriots’ loss to the Eagles in the Super Bowl Feb. 4.

Brady also won’t be in attendance, as he is returning from a trip to Qatar with the charity Best Buddies. As of now, there is no indication that Brady will skip any more offseason practices.

Monday’s practice marks the beginning of the Patriots’ nine-week offseason program and is completely voluntary, per the terms of the NFL’s collective bargaining agreement.

Gronkowski’s absence isn’t a big deal in the micro sense, as the practice only entails strength and conditioning — no footballs, no pads, and no coaches allowed on the field. Plenty of players skip offseason workouts, and it has no bearing on their performance in the fall.

But Gronkowski’s absence on Monday is certainly noteworthy, in that he is making clear to Bill Belichick, Robert Kraft, and the rest of the world that he is displeased with his contract. Gronkowski also appears to be openly feuding with Belichick about his use of trainer Alex Guerrero, whose workout methods sometimes conflict with what Belichick and the Patriots trainers endorse.

And Gronkowski is setting the tone that he’s willing to forgo a $250,000 offseason workout bonus in order to get a new contract. Gronkowski earns the bonus if he attends 90 percent of offseason workouts, meaning he can only miss three of the approximate 36 practices held over the next two months. The only mandatory practices are on June 5-7 during the team’s minicamp. The Patriots can’t punish Gronkowski for missing any voluntary workouts, but they can fine him a total of $84,435 if he skips all three days of minicamp.

Gronkowski has been in the Foxborough area over the last month, working out at the TB12 facility at Patriot Place and appearing at community functions. He has two years and between $17 million-$19 million left on his contract, depending on how many games he appears in.

This marks the second straight year that Gronkowski has grumbled about his contract. Last year, as Gronkowski was set to make $5 million, the Patriots agreed to tack on a three-tiered incentive package that would have paid him an extra $1 million, $3 million, or $5.5 million based on statistical benchmarks and honors. Gronkowski had another dominant season with 69 catches, 1,084 yards, and eight touchdowns, and earned the entire $5.5 million incentive package by being named first-team All-Pro at the end of the season.

Gronkowski is still working off an eight-year, $56 million contract he signed before the 2012 season. His career prospects were uncertain when he signed it, as chronic back problems threatened to end his career prematurely. But now that Gronkowski has established himself as a bona fide star and likely Hall of Famer, his contract has become one of the best values in the NFL.

While Gronkowski will make between $8 million-$9 million this year, top wide receivers are making $16 million per year. And less-established tight ends, like the Bears’ Trey Burton, are making $8 million per year.

But the money isn’t the only issue between Gronkowski and the Patriots right now. When Gronkowski admitted immediately after the Super Bowl that he was considering retirement, it wasn’t a knee-jerk reaction. Gronk reportedly was miserable for much of last season and considered retirement all the way back to training camp last August.

And Gronkowski is one of several veterans, including Brady, who appears to be growing weary of Belichick’s tough coaching style. Brady’s wife said in the “Tom vs. Time” documentary that Brady just wants to “feel appreciated,” and former receiver Danny Amendola, who signed with the Dolphins last month, told ESPN last weekend that Belichick was tough to play for, and openly questioned Belichick’s decision to bench Malcolm Butler in the Super Bowl.

“He’s an [expletive] sometimes,” Amendola, who signed with the Dolphins last month, told ESPN last weekend. “There were a lot of things I didn’t like about playing for him, but I must say, the things I didn’t like were all in regards to getting the team better, and I respected him.”

Gronkowski also has openly sided with Guerrero and Brady in their squabble with Belichick. Gronkowski credits Guerrero for improving his flexibility and helping him endure the rigors of a long NFL season, and regularly posts about his workouts on social media.

Belichick revoked Guerrero’s special access with the Patriots midway through last season, no longer allowing him to fly on the team plane, stand on the sideline during games, or have his own work space inside Gillette Stadium.

Ben Volin can be reached at ben.volin@globe.com. Follow him on Twitter @BenVolin.