PEORIA, Ariz. -- It was 6:30 a.m. on Saturday morning and the Arizona Diamondbacks' clubhouse was not yet open, but there was Tim Locastro sitting in the parking lot anxiously waiting.

After spending 10 days in isolation following a positive COVID-19 test, Locastro craved being around his teammates again.

"I was completely bored," Locastro said. "For the last 10 days, I was stuck in a house for 240 straight hours. I I wanted to be on the field more than anything. I mean, seeing my teammates, coaches, it was like the first day of school for me and I had a blast."

D-backs manager Torey Lovullo put Locastro in the starting lineup Saturday and he responded with a pair of singles in two at-bats before being removed after the top of the third.

"Thrilled out of my mind," Locastro said after coming out of the game. "I would say I was a little nervous. I had butterflies but I mean, I just had to get the butterflies going in the right direction. And then once you're on the field, baseball was baseball again."

The D-backs are counting on Locastro to play a key backup role at all three outfield spots, so getting him back in the swing of things with plenty of time before Opening Day was important.

Sitting around is not something that Locastro enjoys, so he found several things to keep himself occupied.

After setting a goal of getting to 1,500 pushups in one day, Locastro got as high as 800 before finally quitting. He said he was able to get to 230 during his best hour.

"I mean, I was bored out of my mind," Locastro said.

'B' game action
Merrill Kelly started against the Cubs in a "B" game Saturday morning rather than face the division-rival Padres and he went four scoreless innings plus one batter, allowing three hits and a walk while striking out two.

Kelly faced Jake Marisnick and Anthony Rizzo a combined seven times as they were the first two hitters in every inning.

Kelly also got two plate appearances and bunted both times.

Meanwhile, Wyatt Mathisen hit a home run and doubled off the left-field wall.

Mathisen is attempting to win a backup job. An infielder by trade, he has played the outfield in both of the team's B games this spring, as the team tries to increase his versatility.

"My conversations with him have been easy enough that it has left me feeling that he’s gaining comfort out there with each pitch," Lovullo said. "It’s not perfect. He’s an infielder trying to transition to the outfield and get some reps out there. But he’s been doing a ton of work with [outfield coach Dave] McKay prior to the two starts and we’ve just got to raise the comfort level and we’ll see where that takes us."

Game notes
• Trayce Thompson, who is competing for an outfield spot, went 2-for-3 with a home run that sailed over the 410 sign in center.

• Josh VanMeter and Ketel Marte also homered.

• J.B. Bukauskas tossed a scoreless inning. In four outings and four innings this spring he has yet to allow a run.

• Chris Devenski, who is also competing for a bullpen spot, had his third scoreless outing of the spring.

Up next
Left-hander Caleb Smith will make his third start of the spring Sunday when the D-backs play host to the Giants at Salt River Fields. Lefty Alex Young and right-hander Chris Devenski are also expected to pitch.