Mikolas was acquired by the Pirates on Nov. 25 along with outfielder Jaff Decker for first baseman Alex Dickerson. Mikolas spent parts of the past two seasons with the Padres at the Major League level.
He made just two appearances last season and did not allow a run in 1 2/3 innings. He spent most of the season at Triple-A Tucson, going 4-2 with a 3.25 ERA in 54 games. In 61 innings, he allowed 62 hits, walked 17 and struck out 40. He also had 26 saves.
Mikolas, a seventh-round pick in the 2009 First-Year Player Draft out of Nova Southeastern University, pitched in 25 games for the Padres in 2012 and was 2-1 with a 3.62 ERA. In 32 1/3 innings, he allowed 32 hits, 15 walks and 23 strikeouts. Mikolas, 25, relies mainly on a fastball that averages 93-94 mph and a curveball as well as the occasional changeup.
"He has power stuff out of the bullpen," Rangers pro scouting director Josh Boyd said. "We've seen him run his fastball up to 98 [mph] and sit in the mid 90s with ease. His curveball has 12-6 power bite to it and gives him a real weapon late in a game."
Rangers amateur scout Cliff Terracuso recruited Mikolas to Nova Southeastern and coached him there. Special assistant Scott Littlefield knows Mikolas from his previous time in the Padres' front office, and pro scout Mike Anderson has followed him closely over the past few years.
McGuiness played in 10 games for the Rangers this past June while Mitch Moreland was on the disabled list, and he recorded six hits in 34 at-bats, with a double and one RBI. McGuiness spent the rest of his time at Triple-A Round Rock and hit .246 with 11 home runs, 63 RBIs and a .423 slugging percentage in 104 games.
Mikolas is the third right-handed reliever acquired by the Rangers and added to the 40-man roster this offseason. The Rangers also claimed right-hander Chaz Roe off waivers from the D-backs and Shawn Tolleson from the Dodgers. In addition, the Rangers have signed pitchers Justin Germano and Jose Contreras to Minor League contracts.
All will come to camp and compete for a spot in a crowded bullpen.
The Rangers re-signed right-handed setup reliever Jason Frasor early in the offseason, bringing him back into a bullpen that will also include left-handers Robbie Ross and Neal Cotts, as well as right-handers Neftali Feliz, Tanner Scheppers and Joakim Soria.
Other candidates for the bullpen include right-handers Matt West, Cory Burns, Lisalverto Bonilla and Ben Rowen, and left-handers Joseph Ortiz and Michael Kirkman.
Ortega, who spent last year at Double-A Tulsa, was claimed off waivers from the Rockies on Nov. 27. The Rangers have 10 days to trade him, release him or send him to the Minor Leagues through outright waivers.