Neither pitcher was ranked in the Orioles' Top 20 prospects per MLB.com, although Blackmar, 22, posted a 10-1 mark with a 3.18 ERA for Class A Frederick of the Carolina League (26 games, 18 starts). Over Blackmar's last 10 starts, the right-hander produced a 6-0 record with a 2.09 ERA and yielded 45 hits over 64 2/3 innings.
"He's had a very productive year this year," said White Sox general manager Rick Hahn of the 6-foot-3, 215-pound Blackmar, speaking to the media during Saturday night's 8-4 loss to Detroit. "Intriguing kid. Good pitcher's body, nice mix, has some sink, command of his offspeed pitches. That's translated to a fair amount of success in the Carolina League so far.
"Chalas has the bigger arm of the two. He's a reliever prospect. Chalas with the bigger fastball and a little bit more of a project."
Ultimately, this deal isn't as much about the prospects they obtained as it is about the prospects who will be joining the White Sox on Tuesday when rosters expand. The White Sox save the remainder of De Aza's $4.25 million salary for 2014, and while De Aza and Beckham would have commanded somewhere in the $10 million range combined through their third year of arbitration in 2015, they most likely weren't part of the club's plans going forward after this season.
Hahn won't know about the 2015 budget until the whole process is worked through in November. But he will be able to look at potential replacements such as Jared Mitchell, Jordan Danks and Marcus Semien during September.
"There's opportunity for someone to step up and seize that job," Han said of left field. "If not, it's something we are going to be looking to fill in the offseason. We are going to the offseason with a possibility of having someone else out there."
"You are going to have some guys up here that those are positions that now have opportunities," said White Sox manager Robin Ventura, who found out about the trade midway through Saturday night game. "You are going to see some guys in there that are different than what we've had for the last couple of years. They are going to get a chance."
De Aza, 30, had a .243 average with 19 doubles, five triples, five homers, 31 RBIs and 15 stolen bases in 122 games with the White Sox this season. He struggled over the past two years, both with the glove and on the basepaths, but Hahn termed the one-time waiver claim as "somewhat of an underrated player for us."
But it's time for the White Sox to give someone else an opportunity.
"Try to find who else potentially could fit in with what we are building here," Hahn said. "The motivation behind this not only being the two arms that we received back, both of them we believe have a fair amount of upside and add to our pitching depth, but also as with the Beckham move, to free up not only a little bit of salary flexibility going forward, but also some playing time for some of the younger guys over the last few weeks of the season."
In regard to other potential waiver claim deals prior to Sunday night's 11 p.m. CT deadline, Hahn added, "we are going to keep working and exploring some opportunities."