For his efforts, the slugger -- who turned 32 on Saturday -- received a belated birthday gift, as Guillen was named the Bank of America Presents American League Player of the Week.
Although his bat has become a sore spot for opposition, Guillen has been hampered with right shoulder soreness and pain in his hip flexor throughout the season's first seven weeks. Impressively enough, the veteran has managed not only to persevere, but to thrive.
"It certainly makes sense," Royals manager Trey Hillman said, about Guillen hitting better with the injury, "because he was a little slow with his lower-half movement and more controlled. And I think that gave him a little better balance position to be able to fire back."
Last week, Guillen certainly appeared to have his fire back. In the designated hitter slot for a three-game series vs. Detroit, Guillen went 2-for-4 with a home run and three RBIs on Thursday, helping cap a sweep against the AL Central rival.
The outfielder's current hitting streak, 10 games as of Monday, has helped elevate his batting average well over the Mendoza line (.245) despite a rocky early-season start.
"It's not nice when you see that 1-something," Guillen said of his batting average. "It's always good when you see that 2-something there."
The difference has been minor adjustments at the plate, as Guillen's hot bat has helped the Royals win five of their six games last week.
"It's the same guy, but a different approach now," he said. "I've been working hard every day with our hitting coach and doing everything I can to help this team to win."
Even if it means playing with significant discomfort. During a three-game Interleague series vs. the Marlins, the club couldn't use a DH, so Guillen gave Hillman the green light to play him in the field in the National League city.
The move paid off, as Guillen went 6-for-12 with a home run and eight RBIs, and in Sunday's 9-3 win, he collected an outfield assist, throwing out Dan Uggla at the plate.
"Great job, great series," Hillman said. "He takes the pressure off everybody else when he's hitting like that. Great throw from the outfield. He's playing through some stiffness in the hip. Never wants to come out."
Despite his recent surge, Guillen remains even-keeled when explaining his success.
"I'm just working hard, and I keep getting better every day," Guillen said. "I'm putting in some hard work, and it's just paid off in the right way."
It certainly has. Buoyed by Guillen's team-leading 30 RBIs and five home runs (he is in a three-way tie for first), the Royals enter Monday one game shy of .500 and just two games back from the first-place White Sox in the AL Central.
"We came into some great weather [in Florida], and I'm helping this team to win, and that's why they got me here," Guillen said. "I know there was a lot of concern early in the season, but we've been turning it around the right way."
This is the second time Guillen has received the weekly honor, and his first while with Kansas City.
Rangers outfielder Josh Hamilton, Angels outfielder Garret Anderson, Twins first baseman Justin Morneau and Red Sox designated hitter David Ortiz were also considered for the award. Fausto Carmona of the Indians and Edwin Jackson of the Rays were among the pitchers nominated.
Brittany Ghiroli is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.