"I make clear how it was going to work with the ballclub," said Guillen of his talk with Thome. "And I just don't see him getting that many at-bats.
"That's the biggest worry I have. It was not an easy decision, but the more you hang around, the more years you have, one decision becomes harder than the other. I wanted to let him know right away because he might have other options, and I don't want him to keep waiting for our decision."
Thome certainly appears to have other options. As first reported by MLB.com, Tampa Bay has interest in the left-hander, who sits just 36 home runs away from 600 for his career. Minnesota also has interest, both being talented teams where Thome could contribute to his primary goal of winning a World Series title.
Neither squad would offer Thome full-time work, with Pat Burrell in place at DH for Tampa Bay and Jason Kubel holding the same job for the Twins. It was the same situation for the White Sox, with Guillen not wanting to go with a DH who had no other options but serving as a hitter.
According to Guillen, Thome "was cool" with the final decision despite his expressed interest in staying with the White Sox.
"We understand each other and hopefully we did what's best for both parties," Guillen said. "I told him straight up how we feel, but the reason we are doing all this thing is because Jimmy is the person we are talking about.
"If it was somebody else, we would just let him go the way we do with everyone else and move on. The way we feel about him and the special guy he is, that's why we went through this whole scenario."
While Guillen mentioned Sunday how Thome was the only left-handed hitter he really wanted, he admitted Monday night that this bat in the middle of the order could be explored again in the future. That future date could come as soon as March, if the White Sox realize something is missing during Spring Training.
"It's weird because for as long as I've been here, we always played in the past with the big boys in the middle," Guillen said. "We changed our philosophy and what we want to do is have more speed and other stuff.
"Maybe it will take us a little while to see what we have, but I'm very optimistic. I'm very excited. I don't want to say I'll put my job on the line, but I love what I have. Everything should be set right now, but believe me, I talk to [GM Kenny Williams] every day about the ballclub."
Working with 11 pitchers instead of 12 was not a problem for Guillen, who felt the White Sox top-flight starting rotation and bullpen could get them through without a problem. Ultimately, it came down to the best fit for Thome and the White Sox.
In the long term, Thome will be part of the White Sox. He has been told that once his playing career ends, he has an invitation to return to the organization in a to-be-determined capacity. But in the short term, Guillen wanted to avoid a Major League Baseball soap opera.
When Thome didn't play for two or three days, Guillen didn't want the media to go to Thome about the situation. And Guillen didn't want to have to answer the same questions, as to why he was halting Thome's pursuit of 600 home runs.
"For me, it's all about at-bats," Guillen said. "I don't believe Jimmy can play once or twice per week.
"The toughest conversation is when you release someone. We did not release Jim. We just [aren't bringing] him back."
Scott Merkin is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.