MESA, Ariz. -- First impressions aren’t everything, but a good one can only be a positive for a player entering a heated roster spot competition in Spring Training. In the case of Kyle Muller, his presence on the mound is certainly catching the attention of his coaches.

After taking in Muller’s first bullpen of camp on Wednesday, A’s manager Mark Kotsay casually likened his mix of pitches to that of D-backs lefty Madison Bumgarner. Asked about Muller following his side session on Saturday, Kotsay doubled down on those comments, expanding on the comparison he threw out a few days prior.

“They share a lot of the same qualities and traits,” Kotsay said. “I know Bum rides horses. I don’t think Muller’s on horses yet. But they both like to hunt. They’re both left-handed and they’re both really big. If Muller can find a way to turn out like Bum, we’ve got something there. We’re excited about watching him throw.”

Muller was a key part of Oakland’s five-player return for catcher Sean Murphy in December, rated Atlanta’s No. 1 prospect at the time of the trade. A stacked Braves rotation led to scattered opportunities to pitch in the big leagues over the past two seasons.

With two open rotation slots that will likely be decided largely based on spring performance, Muller brings a strong arsenal that includes a fastball that consistently hits 95-97 mph along with a low-80s curveball and power slider, both of which can generate plenty of swing-and-miss.

The comps didn’t stop at Bumgarner. Watching video on Muller prior to his arrival to Spring Training, A’s pitching coach Scott Emerson couldn’t help but think of another star left-hander with multiple All-Star selections.

“I compare him to Carlos Rodón of the Yankees,” Emerson said. “Very similar build. Very similar delivery. The arm action might be a tad different between the two. But if you put them side-by-side, it’s almost identical. Now, we’ve got to get him to throw strikes and do the things that [Rodón] does.”

Fujinami throws again
Having worked with catcher Shea Langeliers in his first bullpen session last week, new A's pitcher Shintaro Fujinami switched it up in his second bullpen of Spring Training on Sunday by throwing to veteran backstop Manny Piña.

Much like Langeliers did, Piña raved about the stuff he saw from Fujinami, who again threw all six of his pitches during the session.

“The straight fastball was good,” Piña said. “Fastball up and in on righties was very good. I like it a lot. If we mix that in with the split and slider, I think he’s going to be very good.”

While a pitcher having six offerings at his disposal presents a multitude of avenues to keep hitters guessing, Piña -- who is entering his 10th Major League season -- has been around the game long enough to know that there can also be challenges that come with such a diverse arsenal.

“Sometimes all six pitches are not going to work,” Piña said. “Maybe it’s only three or four, or two. We need to figure out what pitch is working best on a given day.”

Fujinami is scheduled to face A’s hitters in a live batting practice session on Wednesday. With Oakland opening up its Cactus League schedule on Saturday, Kotsay indicated that the right-hander will likely make his first appearance in one of the club’s first three games.

On the mend
Deolis Guerra, an effective reliever for Oakland in 2021 who is returning as a non-roster invitee after missing all of last season due to Tommy John surgery, is sidelined from throwing to begin camp due to a mild lat strain. Kotsay did not have a timeline for when he might resume throwing.

“He’s still progressing,” Kotsay said. “I’m sure from Guerra’s standpoint it’s disappointing because he was back playing catch and feeling good. But this is a minor setback. I wouldn’t say it set him back more than a couple of weeks.”

Pitching plans
JP Sears and Freddy Tarnok are among the pitchers expected to pitch in Saturday’s Cactus League opener against the D-backs at Hohokam Stadium (watch live on MLB.TV).