Greiner split the left-centerfield gap for a two-run double in the top of the second to give the Rafters a 2-1 lead. He came to the plate in the seventh inning with his team holding a 3-2 lead, and he promptly extended the advantage with a soaring, solo home run to left field that drew many "oohs" and "aahs" from the fans at the Peoria Sports Complex.
The shot came on a one-ball, two-strike fastball. Greiner has been strikeout prone with 191 strikeouts over 206 Minor League games. Greiner had only homered 12 times in his Minor League career, making the timely dinger even more impressive.
"When hitters get in trouble is when they start guessing," Greiner said. "I tried not to guess what pitch he was going to throw me. I was just trying to see it and react. He threw me a fastball inside, I spun on it. Luckily, I was able to keep it fair, get it up and get it out of here."
Greiner came out of the gates hot in his Minor League career, batting .322 in 26 games for Class-A West Michigan in 2014. However, things stalled a bit in 2015 as he hit .183 with a .254 on-base percentage over 89 games for Class-A Advanced Lakeland.
"I had a rough 2015, so I worked really hard in the offseason and put in a lot of effort to revamp my swing," Greiner said.
The work paid off.
Greiner picked up his hitting in 2016, earning two promotions over the course of the year, including one game for Triple-A Toledo. He hit .312 with a .385 on-base percentage for Lakeland against the same level of pitching that had stifled him the previous season.
"I had a good 2016, but that's in the past," Greiner said. "The Fall League is the best competition we can face and I want to build off what I had in this past season."
Although Arizona Fall League teams are made up of prospects from different organizations, Greiner said winning and competition remain important.
"It's a nice honor to be here, but at the end of the day it's still baseball," he said. "You still want to win the game and help your team win. It's really fun playing with these elite players and facing elite pitching. It's fun playing with this competition."
Brendan Kennealy is a senior sports journalism student at Arizona State University. This story is part of a partnership between MLB.com and ASU's Walter Cronkite School of Journalism and Mass Communication. This story was not subject to the approval of Major League Baseball or its clubs.