This year, San Francisco's No. 2 prospect jumped to Class A Advanced and was one of the youngest regulars in the California League at age 20. He also was one of best hitters, coming in seventh in the batting race at .304. He's a career .303/.348/.448 hitter in the Minor Leagues.
So it's no surprise to see Arroyo succeeding against quality pitching in the Arizona Fall League. He had a streak of four straight multi-hit games and hit .440/.464/.720 in his first six contests for the Scottsdale Scorpions.
One of the youngest players in the league, Arroyo said he views his AFL assignment as an honor and a huge opportunity.
"It will definitely help facing pretty good pitching," Arroyo said. "High A in the Cal League, you've still got some pretty good arms. But coming out here, day in and day out, you're going to see velo, you're going to see good breaking balls, stuff like that. I'm just going to keep working on my approach against more advanced pitching."
A right-handed hitter, Arroyo has outstanding hand-eye coordination that allows him to barrel balls repeatedly. He almost makes contact too easily because it cuts into his walk totals.
More selectivity would make Arroyo more dangerous at the plate and allow him to further tap into his power. His pop mostly comes to the gaps at present -- he has 63 doubles and 17 homers in 224 pro games -- though he has gone deep twice in the AFL so far.
The biggest question with Arroyo is where he'll play when gets to San Francisco. Though he's a sure-handed defender with a solid arm at shortstop, he lacks the speed usually desired at the position. The big league club has Brandon Crawford at shortstop and Joe Panik at second base, so Arroyo might fit best at third base, where he'd have to contend with Matt Duffy.
The Giants have no immediate plans to move Arroyo, and they believe he has the quickness to make plays. If he keeps hitting like he has, they'll have to find a place somewhere in their lineup for him. He said improving his defensive footwork is on his AFL to-do list.
"I'm open to anything," Arroyo said. "I'm just trying to play the game. At the end of the day, the goal is to be in the big leagues, whether it's at short, second, third, wherever they want to play me. I'd love to stay in the infield, but that's their decision."
Giants hitters in the Fall League
• Austin Slater, 2B/OF -- Another offensive-minded infielder, he was mostly an outfielder at Stanford and in his 2014 pro debut after signing as an eighth-rounder. He hit .294/.334/.381 between Class A Advanced and Double-A in his first full pro season.
• Mac Williamson, OF -- A third-round pick from Wake Forest in 2012, he missed most of 2014 because of Tommy John surgery but bounced back to hit .275/.368/.433 with 13 homers in 123 games between Double-A and Triple-A this year. One of the best power hitters in the system, he made his big league debut in September.
Giants pitchers in the Fall League
• Ray Black, RHP -- Though he has had problems staying healthy, he may be the hardest thrower in the Minors and already has hit 103 mph in the AFL. A 2011 seventh-round pick from Pittsburgh, he worked just 25 innings in Class A Advanced this year but fanned 51 hitters and posted a 2.88 ERA.
• Phil McCormick, LHP -- A submariner with a mid-80s fastball and a Frisbee slider, he was a 31st-round pick from Missouri in 2011. He spent 2015 in Double-A, recording a 2.04 ERA in 58 appearances.
• Adalberto Mejia, LHP -- He returned from a 50-game suspension for using a banned stimulant to go 5-2 with a 2.45 ERA in 12 Double-A appearances (nine starts) this summer. Signed out of the Dominican Republic in 2011, he shows three-pitch promise with a low-90s sinker, low-80s slider and sinking changeup.
• Dan Slania, RHP -- A fifth-round pick from Notre Dame in 2013, he can miss bats with his 91-95 mph fastball as well as his slider and splitter, but he gets hit more than he should with that stuff. He had 16 saves, a 3.53 ERA and 90 strikeouts in 71 1/3 innings in Class A Advanced in 2015.
This story was not subject to the approval of Major League Baseball or its clubs.