Guerra, who is out of options, was designated for assignment by the Dodgers on March 16. The Dodgers apparently couldn't find a trade partner for the right-hander, who will join fellow old friend Ronald Belisario in Chicago's bullpen.
Guerra tweeted, "I want to thank the Dodgers organization, fans and my teammates for a great 10+ years. Its a bittersweet day and Im excited to be a White Sox and can't wait for this new opportunity."
Rosin was a Rule 5 pick from the Phillies (the Mets actually picked him, then traded him to the Dodgers for cash) and was in a similar situation to Guerra in that the Dodgers couldn't send Rosin to the minors without first clearing hurdles. Rosin would have had to remain on the active roster all season, and with seven guaranteed contracts already in the bullpen there was limited space.
"Obviously I'm thinking about it but I'm not going to let it dictate my week. I'm just going to go about my business and work hard every day," Rosin said on Tuesday. "I was talking to my roommate in college, [NFL wide receiver] Eric Decker, who said 'All you can do is work really hard and let everything take care of itself, that takes the pressure away.' I'm just going to stick to that plan this week and try to enjoy my time here. Hopefully I'll get out there again against the Angels in the Freeway Series and show what I can do."
The Dodgers could have made a trade with the Phillies to keep Rosin on the roster (as someone who could be optioned), but obviously that didn't work out. Before the Dodgers could offer Rosin back to the Phillies - for $25,000, half of the Rule 5 fee - he first had to clear waivers. He nearly did clear waivers; claiming priority is inverse order of 2013 record, with the same league first, meaning Rosin was unclaimed by every National League team and nine American League teams.
Texas will be subject to the same Rule 5 restrictions with Rosin. He will need to remain on their active roster all season or the Rangers would have to expose him to waivers and, if he clears, offer him back to Philadelphia.
Rosin did get two games of major league service time during the Dodgers' trip to Australia. He closed out the win in the exhibition game against Team Australia, though he was the only one of 12 Dodgers pitchers who didn't pitch against Arizona.
"It was an honor to be on the roster and have the opportunity to maybe get in the games," Rosin said.
Thank you Dodgers for everything. It was a great experience with many lessons that will help me with my career. Now on to the next step.— Seth Daniel Rosin (@SethDanielRosin) March 26, 2014
After the moves, the Dodgers have 39 players on their 40-man roster.