On that day, Wood was a 21-year-old flame-throwing phenom, the latest big, strong right-hander from the state of Texas with his whole career ahead of him.
On Friday, that career ended, as Wood completed his 14-year Major League career in the Cubs' 3-2 loss to the White Sox at Wrigley Field.
"It's time -- it was time," Wood said. "We saw how things were going this year, and not being able to recover and bounce back and do my job, essentially, and do what I was supposed to do, day in and day out. The grind of getting ready every day and go through hours to get ready for 15 pitches and not be successful, it was just time. It's time to give somebody else a chance."
Wood's career more-or-less began with that historic 20-strikeout gem. When he was on, like on that May afternoon and so many other times throughout his career, he was one of the best pitchers in the game.
"Great pitcher and one of the great guys," Brewers third baseman and former teammate Aramis Ramirez said. "When healthy, he was one of the toughest pitchers in the game. The numbers back that up."
"He wasn't fun to face. He was, stuff-wise, as good as it gets," former teammate Austin Kearns said. "And effectively wild too. He was as good as it was when you talk about stuff."
Wood began his career in 1998 as a promising young starter. He ended it Friday as a reliever, starting off White Sox outfielder Dayan Viciedo with a 96-mph fastball and tossing his final pitch, a curveball in the dirt, to get Viciedo swinging to cap his career with one last strikeout.
"To let him go out that way, he deserves it. He's been a good pitcher here in the city for a long time," White Sox manager Robin Ventura said. "Everybody should be able to go out ... not everybody gets to ... but it was nice he gets to go out like that."
In between, there was an 86-75 record, 3.61 ERA, 1,582 strikeouts in 446 games and numerous injuries that no doubt robbed Wood of a chance to become one of the premier pitchers in the game's history.
"Tremendous stuff. Overpowering stuff. Dominant stuff," Yankees manager and former Cubs catcher Joe Girardi said. "Most every day he went out there, especially before he had the arm surgery, he had no-hit stuff."
Wood underwent Tommy John surgery in 1999. Six years later, he underwent another arm surgery and in 2005 had surgery on his knee before partially tearing his rotator cuff later in the season.
In all, Wood was placed on the disabled list 16 times in his career.
"The only thing with Woody -- you wish, 'What might have been had that incredibly gifted right arm not gotten hurt so much?'" Grace said.
Although his body couldn't hold up through the rigors of being a starting pitcher, Wood continued his career out of the bullpen, where he was just as successful. He was an All-Star as a starter in 2003 and was again named to the All-Star squad as a reliever in 2008, when he notched 34 saves.
Wood spent the rest of his career pitching in late-inning situations and, in his only two seasons away from Chicago -- in Cleveland (2009-10) and New York (2010) -- he helped the Yankees to the 2010 American League Championship Series.
"He did a tremendous job for us," Girardi said. "He gave our bullpen a huge boost when he got here and pitched extremely well for us."
After his time away from the Cubs, Wood returned to Chicago in 2011, giving the club a hometown discount with a one-year, $1.5 million contract. He signed another one-year deal prior to this season.
"For what he's done for that organization. He was gone and he came back. It was a good legacy he left behind," said Marlins pitcher Mark Buehrle, who spent 12 seasons with the White Sox. "He did everything. He took less money to come back, knowing he wanted to play in Chicago, knowing that's where his heart was."
Reds manager Dusty Baker, who managed the Cubs from 2003-06, said the Reds tried to sign Wood that offseason. Instead, Wood went home.
"He loved Chicago and Chicago loves him. He wanted to retire in Chicago," Baker said. "I thought it would be the end of the year. When the time calls, it's time to go."
A big part of Wood's time in Chicago the last two seasons was mentoring young members of the Cubs' bullpen, such as left-hander James Russell and right-hander Jeff Samardzija -- who moved to the rotation this year. Those two were just the latest examples of Wood embracing his veteran leadership role.
Wood's time in Cleveland didn't go as smoothly as he had hoped, but Chris Perez -- who was groomed as Wood's successor -- said Wood was a valuable teammate.
"It didn't matter how he was pitching or what he did that night, he was always a good teammate, which is important in this game because you're not always going to be doing your best," Perez said. "When that happens, good teammates seem to stick around. I just learned how to be a professional."
Because of his numerous surgeries and time spent rehabbing, Wood was an obvious go-to guy when others suffered the same fate. Red Sox left-hander Rich Hill, who came up with the Cubs, had Tommy John surgery last season. Hill said Wood was the first person he called after he suffered his injury and described Wood as "a really positive guy and great teammate."
"He's done so many great things in Chicago and the people love him there. He's had a long career," Hill said. "With everything that he helped me with as far as even leading by example and, you know, being a professional. For me, I have nothing but good things to say."
Hill's thoughts are shared by Wood's other teammates.
"He was one of my favorite teammates. I had a lot of them, but Kerry was a guy that I hung out with a lot, spent a lot of time with," Grace said. "I attended his wedding in Hawaii. He's a guy that will always be special to me."
Said Ramirez, who added Wood told him last weekend when the Cubs were in Milwaukee that his arm wasn't 100 percent: "You can't find a better teammate."
Wood even impressed those who, uniform-wise, were his biggest rivals.
Marlins manager Ozzie Guillen, who managed the White Sox from 2004-11, said he watched Wood's final game Friday and was glad the crowd of 34,937 at Wrigley Field gave him a standing ovation upon his exit.
"Tremendous man. Great human being. Great pitcher. Very touching moment out there," Guillen said. "I was watching the game. Very classy people in Chicago, giving him a standing ovation. They appreciate what he did for the Cubs, and baseball, period. He's a class act."
White Sox catcher A.J. Pierzynski said Wood was not only good for the city of Chicago, but for all of baseball.
"I love Kerry Wood," Pierzynski said. "Classy guy, a guy I got to know over the last few years, playing against him, being around him. ...
"It's kind of poetic justice that he struck out the last guy he faces."