The Cubs' top prospect homered, doubled and drove in three runs Tuesday night, but the Mesa Solar Sox dropped a 6-5 decision to the Salt River Rafters in the AFL opener for both teams.
Baez went 2-for-4 for the Solar Sox after hitting .333 in 57 games with Class A Peoria. He added 10 doubles and 12 homers for a .596 slugging percentage and collected 33 RBIs to earn a promotion to Class A Advanced Daytona in early August.
"[That felt] pretty good," the 19-year-old shortstop said. "It's fun [to be in the AFL] with all these guys. They're playing the game and doing everything right, just doing the same thing [as the regular season]."
Drafted ninth overall in 2011 out of Florida's Arlington Country Day School, Baez batted .188 in 23 games in the Florida State League but managed to slug .400 with three doubles, four homers and 13 RBIs.
He finished the season strongly, hitting safely in six of his last seven games and closing with a two-homer game on Sept. 2.
As for his plans for the AFL, Baez said he wants to refine his approach and work on a few mechanical things.
"I feel pretty good, just trying to work on slowing my body down, hit the ball to the right side, stuff like that," he explained. "I'm pretty happy [so far], it's pretty fun and I enjoy it. Just keep working hard, have a good fall."
In 80 games across the two levels, MLB.com's No. 23 overall prospect batted .294 with 16 homers, 46 RBIs, a .346 on-base percentage and .543 slugging percentage.
Mesa, composed of players from the Cubs, Orioles, Tigers, Dodgers and Astros, got two hits and an RBI from top Tigers prospect Nick Castellanos and Dodgers infielder Rafael Ynoa.
Rockies prospect Kent Matthes sparked the Rafters' comeback. He homered in the sixth to forge a 4-4 deadlock, then doubled home the tying run in the eighth and scored the go-ahead run on a triple by Chris Owings, the D-backs' No. 5 prospect.
Andy Wilkins also homered and fellow White Sox prospect Trayce Thompson delivered a two-run single for Salt River.
Rockies right-hander Tyler Chatwood started for the Rafters and gave up two runs on four hits while striking out six over four innings. Jarred Cosart, the Astros' top pitching prospect, was charge with a pair of runs on three hits in 3 1/3 frames for Mesa.
Jonathan Raymond is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.