SCOTTSDALE, Ariz. -- Zac Gallen threw his first bullpen session of the spring Tuesday as he works his way back from bursitis in his right shoulder, which could limit his availability for the start of the season.

"It felt pretty good today," Gallen said. "It’s good to throw on the uniform again, go out there, see the guys. Overall felt pretty good."

Gallen said when he started ramping up his throwing in December, he felt some stiffness in his shoulder and went for an MRI.

"Nothing I was super worried about," Gallen said. "I just kind of wanted to be proactive about it. The last thing you want to do is get behind the 8-ball and then the next thing you know you’re playing catch-up. I just tried to be proactive about it. I feel like I’m in a pretty good spot with it. We’re just taking it day by day."

After getting the MRI results, Gallen didn't stop throwing completely, but he also didn't go as hard as he usually does. He will throw another bullpen or two this week, which puts him slightly behind a number of the other pitchers who have already, or will shortly, throw live batting practice to hitters.

Whether he's able to start the year on the active roster remains to be seen.

"I’m going to keep giving [the athletic training staff] as much information as possible to hopefully steer it in that direction," Gallen said of being ready for Opening Day. "At the end of the day they make the main decision. I’ll keep giving them enough information but at the same time being smart about it. Knowing that it is a long season, maybe if it is a little delayed it’s not much. I feel pretty good staying on this pace and being ready for Opening Day."

Kennedy unofficially in camp

The signing of right-hander Ian Kennedy to a one-year contract with a mutual option for 2023 has not yet been made official, but Kennedy was spotted at D-backs camp Tuesday. The signing should become official Wednesday.

Everyone in attendance

Right-handers Mark Melancon and Edwin Uceta reported to camp Tuesday after missing Monday, meaning all 57 players are in camp.

Both Melancon and Uceta were out of the country when the lockout was settled, which made getting back a little more of a challenge for them.

Melancon, who signed a two-year, $14 million free-agent deal this winter, said veteran lefty Madison Bumgarner played a role in his decision to sign with the D-backs.

"MadBum called me every day this offseason," Melancon said. "He's a great influence and somebody I want to compete with. He's a warrior."

Melancon and Bumgarner were teammates with the Giants in 2018-19.

Numbers change

D-backs right-hander Luke Weaver is sporting a new number this year, switching from No. 24 to No. 7, the number he wore during his last year with the Cardinals.

Weaver originally wanted to wear No. 7 when he was dealt to the D-backs prior to the 2019 season, but it belonged to quality control coach Robby Hammock.

Hammock's contract was not renewed for this year and reliever NoéRamirez told Weaver that 24 was his favorite number, so Weaver gave up 24 and took 7.

Only one other pitcher in D-backs history has worn a single-digit number -- Mike Leake, who wore No. 8 in 2019.

Marte out again

Second baseman Ketel Marte missed a second day of workouts due to irritation in one of his eyes from his contact lens. Marte was at camp Tuesday but spent much of the time in the training room getting treatment.