MESA, Ariz. -- Zach Penrod's story is one of the best of this year's Arizona Fall League. It added another chapter Monday night.

The Red Sox left-hander struck out five and scattered one hit and two walks over four scoreless innings in Glendale's 2-0 win over Mesa at Sloan Park. The gem lowered Penrod's AFL ERA to 1.13 through his first two outings for the Desert Dogs.

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The 26-year-old's Fall League comes less than two months after Boston signed him from the Pioneer League, an independent Partner League of MLB. Since the Aug. 15 move, Penrod posted a 2.18 ERA with 20 strikeouts in 20 2/3 regular season innings for High-A Greenville, was the Drive's winning pitcher in the South Atlantic League championship clincher and found out he was headed to one of baseball's premier prospect showcases.

"Otherworldly," Penrod said. "I just keep saying I'm in a dream just waiting to wake up. I'm just trying to enjoy every single moment that I get because you never know when you're going to put the uniform on for the last time."

Penrod knows of what he speaks because he's earned and lost a spot in affiliated ball before. He signed with the Rangers as a non-drafted free agent out of Division II Northwest Nazarene University in August 2018, but was released in June 2020, one year after undergoing Tommy John surgery. He pitched in the Pioneer League in 2021 and 2022 but was off to his best start yet in 2023 (2.98 ERA, 65 strikeouts in 54 1/3 innings) when the Red Sox approached him as a potential arm for their High-A club.

The southpaw performed well enough for the Drive -- including those five innings as the long man out of the bullpen in Game 2 of the South Atlantic League Finals on Sept. 19 -- that the Sox wanted to see more and included him in their AFL contingent.

"I found out about two-and-a-half weeks after getting to Greenville," Penrod said. "I put together a few good starts, they offered me the opportunity and I said, absolutely, yeah. It's just been excitement ever since."

From a stuff perspective on Monday, Penrod was sitting around 92-94 mph with his fastball, touching 96, and was around the upper-80s with his slider and the mid-80s with his changeup. He finished with 66 pitches, 39 for strikes including nine for whiffs.

Red Sox catcher Nathan Hickey spent the second half with Double-A Portland and caught Penrod for the first time Monday. He couldn't help but come away impressed.

"Fastball was electric," said the backstop. "That changeup is unreal. Slider, he had it when he needed it. I thought he had all of his stuff tonight, was commanding it very well, throwing anything in any count. What more can you ask?"

Hickey added that what made Penrod's heater so dynamic was his ability to hide the ball by holding his back leg down the mound, allowing the pitch to play above the velocity. Penrod himself noted that he'd added some velo on the heater too in 2023, bumping it up from 90-93 to 92-94 as he's grown more confident across multiple levels.

It's early days in the Fall League, but after Monday's outing, Penrod sits tied for second in the prospect-laden circuit in both innings pitched (eight) and strikeouts (nine), trailing only No. 31 overall prospect Ricky Tiedemann in both categories.

"Honestly, I've rolled confidence over," he said. "I felt like I had the ability and my stuff played well enough that I could take it here and see what I could do against these hitters."

"His story just makes him who he is," Hickey added. "Coming into tonight, I'd only heard great things, so I was expecting him to come out here and shove. He did that."

No. 24 A's prospect Royber Salinas was a worthy opposing starter to Penrod, having struck out six and allowed one unearned run on three hits over three innings. Red Sox outfielder Corey Rosier went 2-for-5 with an RBI and a stolen base as the only player for either side with multiple hits.