On Sunday, his historic night surprised even himself.
The switch-hitting shortstop went 4-for-4 and tied a team record with eight RBIs as the Aeros beat the Bowie Baysox, 11-8.
"I think this is the first time in my career," Diaz said of his big night through a translator. "It was a big game. I'm really happy and excited.
"This is my first time with eight RBIs. I think five RBIs was my most before. I have no explanation."
Akron entered Sunday's game having dropped nine of its last 12 games, including six of the previous seven. As a result, the Aeros had seen their lead atop the Western Division shrink to two games.
On Sunday, Diaz took it upon himself to make sure the team will have sole possession of the league lead when the second half of the season gets underway Thursday.
Acquired by Cleveland in the deal that sent Russell Branyan to Seattle in 2010, Diaz hit an RBI single up the middle with two outs in the first inning and he doubled home two runs before the Baysox recorded an out in the third.
"I was attempting to bunt early in the at-bat, but at 1-0, I pulled it back because I was expecting a fastball. I got a fastball and I was able to drive the ball," Diaz said of his 15th double of the season.
The 23-year-old then slugged a grand slam -- his first of the year and the Aeros' second of 2012 -- off new pitcher Zach Clark with two outs in the fourth before driving in an eighth run with a two-out hit to left field in the sixth.
"The previous batter walked on four straight balls to load the bases," he said of his home run at-bat. "In the on-deck circle, I was thinking about a breaking ball. Then I got a first-pitch curveball and I put a good swing on it."
The Baysox intentionally walked Diaz with two outs and a runner on second in the eighth.
"I was definitely thinking that with the night I was having that a fifth hit could have been a possibility," he said.
Diaz's eight RBIs topped his previous single-game high by three, while his four hits tied his personal best. Playing for Class A Advanced High Desert on May 14, 2010, Diaz went 4-for-5 with two homers and five RBIs in an 11-inning 10-9 victory over the Stockton Ports.
It was Diaz's 16th multi-hit game of the season and his fifth career four-hit performance. It was also his fifth game this year with more than one RBI.
The eight RBIs tied a franchise mark first set by Scott Morgan on May 25, 1999, against New Britain and replicated by Matt McBride on July 31, 2009 against Binghamton.
It was also the most RBIs by a single player against Bowie in Baysox history. Altoona's Adam Hyzdu (May 5, 2001) and Binghamton's Ramon Espinoza (June 20, 1997) each plated seven runs more than a decade ago.
Diaz, a native of Bani in the Dominican Republic, raised his season average to .260 in the victory. He is batting .378 with 14 RBIs and eight runs scored over his last 10 outings and he has hit safely in 17 of his last 20 contests.
"The reason for my success over the last few weeks is because I've continued to work hard every day," said Diaz, originally signed by the Mariners as a non-drafted free agent in 2006. "If I don't get it done one day, the next day I will go out and work even harder."
Diaz is now in his second year playing at the Double-A level. Last year, he hit .255 with nine homers and 60 RBIs -- both career highs -- in 133 Eastern League games. He also smacked 24 doubles, another personal best, legged out four triples and swiped nine bases.
In five big league games with the Indians the last week of May, Diaz batted .267 with four singles and four runs scored.
On Sunday, Jose De La Torre (7-0) allowed one run on three hits and two walks over 2 1/3 innings in relief of Brad Brach, who yielded three runs on six hits and a pair of walks over the first 2 2/3 frames.
Bowie starter Bobby Bundy (2-11) surrendered five runs on seven hits and a pair of free passes over the first three innings in the losing effort.
Nick Markakis, rehabbing a fractured right hamate bone, went 1-for-4 with a double and a run scored. Catcher Taylor Teagarden, on the DL with a lower back injury, drew a walk in his only plate appearance before leaving the game after the top of the third.