He posted a .646 OPS in winter ball. He hit .163 in the minors for us. But I'm not basing everything on his performance against weak competition. I watched him play when he was in Atlanta. What I saw was a guy who struggles mightily to make solid contact and, honestly, I didn't care for his swing. Olivera's game is based on spraying line drives all over the field. He's not a lumbering power hitter with a great batting eye and huge swing that yields few hits but lots of HRs. If he's going to struggle making solid contact he's not going to give us much.
But I'm just a fan. Lets see if my observations were backed up by stats.
According to Fangraphs, 14,7% of his batted balls were hard hit, 52.9% were medium, and 32.4% were softly hit. A line of 20% hard hit , 55% medium, and 25% soft is considered "awful". Fangraphs doesn't list anything below awful. His LD% was 16.2% while league average is 21%. His infield fly ball percentage was 25%, league average is 11%.
This tells me that I was right in what I was seeing. Olivera was very, very bad at barreling the ball and hitting it with authority. This coupled with the fact that he's been unimpressive against inferior competition makes me very concerned.