Guillen said he reported to Royals camp about 20 pounds overweight.
So he was asked if that contributed to his early-season hitting woes.
"It's no excuse, but I'd probably say yes right now," Guillen said. "The weather's had a lot to do with it. I know myself, and I knew that sooner or later, the way I was working, I was going to get out of that slump that I was in. Because if you'd see me in the first month, you'd say, 'Who is this guy? This guy is not the player we're expecting to have in here.'
"But, in baseball, things change, and on any given day, you can just go and start. You hit one ball hard and you say, 'OK, I've got it now,' and you're OK from that point on."
Certainly, he seems OK now with a torrid 10-game hitting streak raising his average from .165 to .245 as of Monday.
"When you show up pretty much out of shape like I did this year and have to lose a lot of weight, that's not good," Guillen said.
"As a player, this is your job, and you've got to make sure you stay in good shape. Because when you come out of shape and you're trying to get into shape for the season, you're always going to have a hard time."
How much did he weigh when he checked in at Surprise, Ariz.?
"Oh, 235, maybe a little bit more than that," he said.
"Oh, I think I'm like 216, 210, something like that," he noted.
During the offseason, the Royals had invested $36 million in a three-year contract for Guillen, and the player, a hard worker at heart, was disappointed in himself.
"That's the truth," Guillen said. "It kind of drove me crazy. The last two years, I kind of showed up for Spring Training out of shape. It's a big responsibility when a team gives you a lot of money like this. You've got to come in better shape."
At the time, there was no talk about Guillen being overweight.
"It doesn't look like I'm showing up in bad shape because [of the way] my body is built," Guillen said. "I have such big legs and stuff, it doesn't look like it.
"It really drives me crazy, all the hard work I have to do to get myself in shape."
Well, except for a still stiff right hip flexor, he seems in fine shape now. Going into Monday night's game against the Red Sox, he was on a 10-game tear with 19 hits in 38 at-bats and 15 RBIs.
Manager Trey Hillman had Guillen as the designated hitter on Monday, because the hip remained a bit sore after he played left field for three Interleague games in Florida. Guillen twisted it while running the bases on Sunday.
With Joey Gathright's left shoulder still hurting from Saturday's outfield collision with David DeJesus, the left-field spot was filled by utilityman Esteban German. Besides, that provided another right-handed hitter against Red Sox lefty Jon Lester.
"[German] came out and worked on it early," Hillman said. "He takes balls off the bat good, and we don't have any guys that can climb the wall."
Told that German said he just might climb the Green Monster to catch a ball, Hillman smiled.
"If he wants to be Spider-man, that's fine with me," he said.
Hillman was pleased that Guillen was named the American League Player of the Week on Monday, and pleased with the way he's come back and pleased that he admitted he was out of shape this spring.
"I'm really proud of the way he's handled himself," Hillman said. "The guy's accountable."
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.