"I need to get better at getting the pitches down; don't leave the pitches up," Mendez said with the help of teammate and translator Jorge Cortes. "I have good stuff. I need to locate the pitches where I want them."
Mendez knows enough English to communicate with Tennessee pitching coach Dennis Lewallyn, who in turn knows enough Spanish to understand Mendez. Plus, the language of baseball can be universal.
"I think it's a combination of everything you just said," Lewallyn said. "I played six years of winter ball, and I've coached it for a couple of years. I've done Venezuela, the Dominican Republican and Puerto Rico. I went to a Caribbean series in Mexico so I've been around.
"I can order in a restaurant and I can get around town, and I know the baseball terminology. I can communicate with him, and he speaks pretty good English. We communicate well," added Lewallyn.
Mendez only echoes that assessment of their rapport.
"I have a good relationship with him," Mendez said of Lewallyn. "I understand. Everything is good with him."
The best communication occurred when Mendez recently told Lewallyn and Barbaro Garbey, the team's hitting coach, that he was not comfortable on the mound because of his arm mechanics.
"He finally told me and Barbaro a couple of weeks ago that he just wasn't comfortable with his arm angle," said Lewallyn, who is in his first season with the Cubs and had not seen Mendez pitch prior to this year.
"Come to find out, somebody had suggested that he raise his arm, get a little bit higher with his arm angle, and he wasn't having a lot of success. He's trying to get back to a lower three-quarter – not side-arm but a lower three-quarter – and he's actually got more movement on the ball there."
Lewallyn added: "But now he's got to find his release points so it's going to be a work in progress, but he does have more movement and he's throwing just as hard so it's a plus."
Mendez will use the last two months of the season to work out those mechanics. If he can do so, his "plus arm," as Lewallyn called it, should get him a shot in the big leagues at some point.
"I have a good chance," Mendez said. "I need to get better, but I know I have that chance. I'm going to go get it and do my best."
Mendez is 2-3 with a 5.32 ERA this season. He has appeared in 32 games and pitched 44 innings with 40 strikeouts and 24 walks. He has one save, four holds and six games finished.
"He's got a plus-arm," Lewallyn re-iterated. "The ball comes out of his hand very nice, and he can pitch every day. He still doesn't command the baseball well enough, and his breaking ball is mediocre, but it's getting better. Not only can he pitch every day, but he wants to pitch every day.
"When you've got an arm like he does, we take our time and you give him as many chances as you can, because it's hard to find many arms like that. It takes some guys a little longer than others," Lewallyn added.
The Cubs are being patient with Mendez because he's a power pitcher with a low to mid 90s fastball that can chew up some innings, especially in middle relief. His game appearances and innings pitched lead the bullpen. He also has some size at 6-foot-2, and is a solid and fit 180 pounds.
"It may sound like a step backwards to change his arm angle, but sometimes you have to do that," Lewallyn said. "I had (left-handed pitcher) Javier Lopez when I was over with the Diamondbacks, and he was a straight over the top guy, and he had no chance to ever pitch in the big leagues like that.
"We dropped him down, and he's got some big league time with the Diamondbacks, the Rockies, and the Red Sox right now. Sometimes you have to make some changes like that, and you have to take a step back to begin progressing again. I think he (Mendez) is on the right track."
Mendez is already showing improvement despite having to make his adjustments midway through the season.
His last appearance before the Southern League All-Star break was on July 3 against the Mississippi Braves. He pitched 2.1 innings, allowed two hits, struck out three, didn't walk a batter and didn't surrender a run.
When Mendez gets the call from the bullpen, he keeps his thought process simple and narrow. He's not thinking about arm mechanics; he's thinking about a short stint on the mound.
"I'm trying to focus on the strike zone," Mendez said. "Come into the game and throw strikes. I'm mentally like, ‘Go there and go one, two, three.' Throw strikes is the most important thing."