CHICAGO -- The White Sox bullpen rates as a work in progress during the organization's ongoing overall rebuild.
But the acquisition of Minor League hurler Thyago Vieira from Seattle on Thursday, in exchange for $500,000 in international signing bonus pool money, could serve as one of the White Sox relief solutions in the short term and long term.
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"We're excited to have been able to acquire Vieira as a potential piece to our bullpen moving forward," said White Sox director of player development Chris Getz. "He possesses elite arm strength, and we believe he has a chance to shorten ballgames for us in the future. The makeup is excellent, and we feel he is a great addition to our organization."
Vieira, 24, went 2-4 with a 4.00 ERA, four saves and 46 strikeouts in 41 appearances and 54 innings between Double-A Arkansas and Triple-A Tacoma in 2017, limiting right-handers to a .194 average. He was selected to compete for the World Team at the All-Star Futures Game in Miami, where he threw scoreless baseball over two-thirds of an inning.
The 6-foot-2, 210-pound Vieira also made an appearance with the Mariners last season, retiring all three batters faced in his Major League debut on Aug. 14 vs. Baltimore. He became the fifth native of Brazil (Sao Paulo) to play in the Majors, joining Yan Gomes, Andre Rienzo, Paulo Orlando and Luiz Gohara. Orlando and Rienzo were once part of the White Sox organization.
Vieira enters the White Sox prospect rankings at No. 20, per MLBPipeline.com. He had been rated the Mariners' No. 8 prospect.
Per the MLBPipeline.com scouting report, Vieira has an 80-grade fastball and a 55 grade on the curve. His fastball sits 97-100 mph and has topped out at 102 mph, with a power curve coming on strong in the last season.
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"Anybody that throws 100, if he throws it over, that will have a chance to play," White Sox pitching coach Don Cooper said.
This sort of raw talent has Vieira as a potential closer of the future. He mixes in with Zack Burdi (No. 12 prospect) as a down-the-line late-innings possibility, and adds another possibility to a group that lost Player Page for David Robertson, Tommy Kahnle, Anthony Swarzak, Dan Jennings and Tyler Clippard last season via trade but still has Juan Minaya, Gregory Infante, Aaron Bummer and a recovering Nate Jones, Jake Petricka and Zach Putnam in the mix for 2018.

"We were able to give many, many opportunities to people because of the circumstances we were under, which we traded everybody and their brother and certainly everybody in the bullpen," Cooper said. "When they left, many new guys got that opportunity.
"I don't look at it as we need this, that or the other thing. That's not my job. My job is to keep my finger on the pulse of the guys that we do have. But this is just [general manager Rick Hahn] making another acquisition of, it seems like, another talented kid, as far as the stuff. So that's exciting."
With the move, the White Sox 40-man roster sits at 36.