The Cubs' No. 4 prospect tossed three perfect innings in his AFL debut Friday afternoon, but the Mesa Solar Sox fell 4-3 to the first-place Salt River Rafters.
"I could tell the first three days, this is really a hitters' league," McNutt said. "[Pitchers] really need to concentrate on working down in the zone and staying ahead."
The 22-year-old right-hander retired five batters on ground balls, two on line drives and two on fly balls. He did not engage in anything longer than six-pitch battle and said his success was easy to explain.
"Them being aggressive and my pitches being good," he said. "They couldn't really do anything with them."
Having not appeared in a game since Sept. 3, McNutt threw 38 pitches but said he would expect that total top 50 by autumn's end.
The 2009 32nd-round Draft pick spent the entire regular season at Double-A Tennessee. In 23 games, including 22 starts, he went 5-6 with a 4.55 ERA. Named a Southern League midseason All-Star, McNutt sported a 2.34 ERA through eight appearances, but his year turned on May 28 when he pitched seven shutout innings against Mississippi but suffered bruised ribs in an in-game collision. He had also battled blisters on his pitching hand.
"I started the season strong. I had the injury at the end of May that carried into the first week of June and it was hard me for to get going, to get sharp again," McNutt said. "The second half, it just wasn't a good half. I [was] trying to take something positive from it. The adversity was probably the best thing for me.
"I just have to get back on track, and that's the reason I am here."
Rafters starter Dallas Keuchel (Astros) made one mistake in his three-inning stint, allowing a two-run homer to Jarek Cunningham (Pirates), who had been 0-for-8.
Salt River tied it at 2-2 in the fourth when Astros prospect Kody Hinze smacked a two-run shot off reliever Cole McCurry (Orioles). Hinze also scored the go-ahead run in the seventh, reaching on a two-base throwing error by pitcher Dakota Watts and coming home two batters latter on Rockies prospect Nolan Arenado's single.
Mesa tied it again in the eighth as Brandon Short (White Sox) tripled and scored on a single by Pirates Minor League Player of the Year Robbie Grossman.
Hinze played a key role in the Rafters' walk-off win. He drew a one-out walk in the ninth and left for pinch-runner David Nick (D-backs), who took third on a single by Ryan Wheeler (D-backs) and scored on Cunningham's throwing error.
Andrew Pentis is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.