This story was excerpted from Steve Gilbert’s D-backs Beat newsletter. To read the full newsletter, click here. And subscribe to get it regularly in your inbox.

The D-backs wrap up a three-game series with the A’s today in Oakland before heading to Pittsburgh and Philadelphia as part of a nine-game road trip. Today, we’re going to take a look at the latest from the Arizona farm system.

TRIPLE-A RENO

After walking more batters than he struck out in April, left-hander Blake Walston is turning in an impressive May, compiling a 1.45 ERA while striking out 17 and walking seven over 18 2/3 innings.

Throwing strikes had not been an issue for Walston before, and whatever the issue was in April seems to have been corrected. Whatever changes were made to help with his command have also translated to better velocity on his fastball, which had dipped into the low 90s/high 80s at one point.

“He's a great athlete and commands the baseball,” director of player development Josh Barfield said. “I know the staff there has done a really nice job, they made some mechanical tweaks, things they noticed he was doing a little bit different from the previous year and the command has been much better last couple times out. His velo has jumped, too. It was up to 95 mph last time out, so it’s been nice to see that climb back up. He’s pitching in Triple-A now, so he’s at the point where he’s considered depth now so we need him pitching the way he has been in case something opens up.”

Outfielder Jake McCarthy, who opened the year in the big leagues, was hitting .258/.356/.419 in his first 16 games with Reno through Tuesday night.

“He went down there with a good attitude,” Barfield said. “He's got incredible makeup. I think that's what's allowed him to be successful. He's gone down there with a good attitude, working hard and just trying to make some adjustments to get back to driving the ball a little bit more like he did last year.”

DOUBLE-A AMARILLO

It was a scary moment for the D-backs on Tuesday afternoon when shortstop Jordan Lawlar, the franchise's top prospect, according to MLB Pipeline, was hit on the right hand with a pitch and had to leave the game. X-rays, though, were negative and he is listed as day to day.

Lawlar is off to a slow start at the plate this year, hitting .178/.305/.374 through Tuesday.

“He's been in a little bit of a rut here the last three weeks or so,” Barfield said. “He’s starting to show signs coming out of it. He’s had some swing-and-miss, but he’s getting back to the good approach that he’s had and I think the numbers and the strikeouts will be where they need to be soon.”

Defensively, though, it’s been all positive for Lawlar.

“He's made some huge strides defensively, which I think we're really excited about,” Barfield said. “He’s put a lot of work in so seeing the strides he’s made defensively is really encouraging.”

A.J. Vukovich has swung the bat well, hitting .274/.325/.491, and has seen time at first base, third base, left field and right field.

“He got a little taste of Double-A last year but this is his first full season in Double-A, and he’s still one of the younger players in the league,” Barfield said. “We’re pretty happy with the performance there so far. He’s improved his approach and he’s walking more than he has in the past.”

HIGH-A HILLSBORO

Infielder Ivan Melendez recently homered in four straight games after a couple of stints on the injured list this year, including once being in concussion protocol after being hit in the face with a pitch.

“Since he's come back, he's been crushing it,” Barfield said. “He seems to be in a really good place right now. His defense at third has been good as well. He played first in college, but we think he’s a good enough athlete to play third, and so far the defense has been pretty solid.”

SINGLE-A VISALIA

Shortstop Jose Fernandez is off to a good start for the Rawhide after spending the past couple of seasons in the Arizona Complex League.

“He’s made some nice adjustments,” Barfield said. “He got stronger and I think having more physicality has helped him. He’s made some adjustments at the plate. The coaches did a really good job with him, kind of simplifying things. He had a nice spring and we decided to push him out to Visalia.”