Known in that he hit .341 with 178 home runs over 10 seasons for Cienfuegos in Cuba. That total included a .453 average over 212 at-bats in 2010. Unknown, though, in the realm of handling Major League pitching over the 162-game grind.
Three seasons later, Abreu has been worth every bit of the $24 million spent so far of his six-year, $68 million deal. But in the context of the White Sox rebuild, it's no longer simply about offensive production for the first baseman. Abreu will have to step into a leadership role among the young players, one he has expertly executed by example as a big leaguer.
That role already has begun naturally via interactions with newly acquired Yoan Moncada, the No. 2 prospect in all of baseball per MLBPipeline.com, a switch-hitting infielder who was teammates with Abreu in Cuba.
"I've been trying to give him some advice, tutoring him about what he can expect, what he can do and what we expect from him," said Abreu through White Sox translator Billy Russo at SoxFest. "I embrace every role the team wants me to play.
"It doesn't matter if it's a mentor role or a leader role, I'm going to be the same player I've been during my whole career. Right now, I'm going to try to do a little bit more teaching these guys how to do well here."
Abreu blasted on to the Major League scene in '14 by launching 10 home runs and driving in 32 runs during March/April. He eventually claimed American League Rookie of the Year honors by hitting .317 with 36 home runs and 107 RBIs.
In each of Abreu's first three seasons, he has batted at least .290 with at least 25 homers and 100 RBIs. His '16 campaign had its ups and downs, with Abreu struggling a bit in the first half to the tune of a .752 OPS, including no home runs and eight RBIs in July.
Some wondered if the 30-year-old's skills were beginning to decline, but it should be noted that Abreu was dealing with personal and family issues in relation to his young son's arrival to the United States during that time. He bounced back with 14 home runs and 44 RBIs over his final 249 plate appearances.
The affable slugger opted into arbitration this offseason despite having three years left on his contract, meaning the White Sox maintain control but he will go year to year. That run ends with the '19 season, a campaign in which the rebuilding White Sox rebuild should be ready to contend.
At that point, Abreu may not be the star of the team or the face of the franchise; if things go to plan, that honor hopefully will rest on Moncada's shoulders. But Abreu still should be a significant contributor for that season, if not beyond.
"I'm glad I'm here right now because I love this team and I want to play for this team for a very long time," Abreu said. "I'm glad to be with all these guys, the new players too.
"We are ready for all the challenges we are going to face during the season and in the future. You have to do your best every single day. That's the way we need to approach the season. There's no other way to do it."