FOXBORO — It isn’t exactly a shock but Rob Gronkowski was the star of yesterday’s Patriots workout.

It was Gronk being Gronk. But in what way? That phrase has come to have a few different meanings.

On the football field, the definition is pretty clear. When Gronkowski is on the job, there’s no one quite like him.

There aren’t many 6-foot-6, 265-pound men who beat safeties down the field, routinely make one-handed catches, or leap up over defenders to make plays.

He’s the best tight end in the game when healthy, and a huge difference-maker in the Patriots offense. The sight of Gronk flying down the right sideline, blowing past safety Jordan Richards yesterday to haul in a high-arcing Tom Brady floater put a nice exclamation point on his day. And if that didn’t do the job, the reverse chest-bump with James Develin in celebration brought it all home.

The trouble with Gronk, of course, has been his downtime. His career has been tinged with injuries, with last year’s season-ending back surgery derailing him for the entire postseason run to the team’s fifth Super Bowl title.

So yesterday, we began the offseason with another Gronk watch. Did he participate in the workout? Was he part-time? Or full-time? How did he look? Did he favor the back?

Let’s start with the basics.

He was full-go in the rain, which speaks volumes in itself. Granted, it’s an offseason workout, but there were no kid gloves for the tight end, who underwent back surgery on Dec. 2.

He looked good reaching to make catches, be it from Brady, Jimmy Garoppolo or Jacoby Brissett. He ran pretty well. He didn’t appear hampered in any way, although at one point, he did need to get down and do a plank to apparently stretch his back.

For the most part, watching him extend to haul in over-the-shoulder passes from Brady in the end zone, like the aforementioned rainbow, or make a quick cut to break open to catch a pass over the middle, this was Gronk being Gronk — the football version.

“He looks like Gronk,” said offensive coordinator Josh McDaniels, providing his assessment of the tight end after seeing him in several OTA sessions. “We haven’t got into a big evaluation. He’s involved in everything.”

Unlike past OTAs, he didn’t take any drills off. He did everything, and performed well. Gronkowski has been telling people he’s felt good during various stops. After missing the latest championship, although he did cheerlead from the sidelines, Gronkowski vowed to be a part of the next one with his teammates.

But will his back, now with three procedures on the books, hold up?

We did see him participate in WrestleMania 33, jumping in the ring to fight WWE star Jinder Mahal. That was Gronk being Gronk — the goofy version. But that cameo provided a glimpse of how the back was coming along.

And, given how the Patriots just reworked the star’s contract, restructuring it with certain statistical thresholds, he’ll be paid like the best tight end in the NFL.

Gronkowski’s prior deal had him at a bargain rate. But the $5.25 million he’s set to earn this year might escalate to $10.75M if he plays 90 percent of the offensive snaps, makes 80 catches, gains 1,200 yards, or is named an All-Pro.

Basically, Gronk just needs to stay on the field to earn top dollar. It’ll be a win-win for the player and the team if that happens. While the Pats did win a Super Bowl without him, their chances of defending their title escalate if he’s in the lineup wreaking havoc with defenses.

But, as has been the case since Gronkowski walked in the door as a rookie in 2010, staying healthy is always a big question mark. Gronk certainly has the incentive to be on the field, but something always seems to happen, whether it’s a back, knee, forearm or ankle.

He’s played in 15 or more games in just four of seven pro seasons. Can the tide possibly change?

Dwayne Allen, Gronkowski’s new sidekick at tight end, has been impressed with Gronk’s work ethic in the short time he’s known him.

“I’ve worked with a lot of tight ends through the years. Gronk’s as hard a worker as anyone,” Allen said. “It’s inspiring to come to work with someone who works as hard as he does.”

Just Gronk being Gronk — the football version.

It’s just one workout, but he’s back, he looks good and seems ready to help bring home No. 6.