"I don't really start evaluating until they start facing hitters," manager Mike Redmond said. "I like what he did today. He threw a few breaking balls and moved his fastball in and out for strikes."
McKirahan threw 12 pitches -- 10 for strikes. One of his strikeouts was against right-handed-hitting Jacob Heyward, the brother of Cardinals right fielder Jason Heyward. Heyward had doubled in his first at-bat.
McKirahan will be one of the most closely watched players in Marlins camp, simply because he is a Rule 5 Draft pick off the Cubs' Minor League roster. By rule, McKirahan has to remain on the Marlins' active roster or be offered back to the Cubs.
Mike Dunn is the lone lefty reliever guaranteed a roster spot. There are candidates for a second lefty in McKirahan, Pat Misch, Grant Dayton and Pat Urckfitz. Chris Narveson, who also struck out three batters his inning of work on Tuesday, is a choice as a long reliever. But Narveson may wind up starting off at Triple-A New Orleans in the rotation.
Lefty Brad Hand, in the mix for a rotation spot, may also wind up in the bullpen.
General manager Dan Jennings made it clear the club would prefer a second lefty in the 'pen.
"You know what? Looking at this division, I think quite honestly, if you can have it, it's a luxury," Jennings said. "It helps put everyone else in the right spots in your bullpen. So, it's something we're looking seriously at."
One reason the Marlins aren't actively pursuing a lefty on the market is because of the candidates in camp.
"I think our answers are here in camp," Jennings said. "We've said that the whole time. It will be fun to see how it plays out."
The book on McKirahan is he has a tick above-average fastball in the low-90s, with a plus slider.
"He's a kid who competes," Jennings said. "A very, very competitive kid on the mound."
A 6-foot-2, 195-pounder, McKirahan has 120 2/3 career Minor League innings, and he features a 2.16 ERA with 128 strikeouts and 35 walks.
"It's a great story to see a guy getting an opportunity around a new team, new place, new eyes [watching him]," Jennings said. "Pretty darn good first impression."