Then, there is the fire, which is constant for every pitch that he is on the field.
Quite simply, Youkilis has become one of the most impactful players in the game, which is pretty impressive when you consider the way it started.
One of the four remaining players from the epic 2004 Boston team that broke an 86-year World Series championship drought, Youkilis was just fighting for a roster spot back then. The fight was even harder the next year, when he continually found himself rotating between the Red Sox and Triple-A Pawtucket.
Red Sox manager Terry Francona began his tenure the same season as Youkilis, so he has had a front-row view of the impressive emergence from bubble player to core player to star.
"He was on that I-95 [shuttle] that one year," Francona said. "He's grown into one of the better hitters in the game, and one of the better defenders. Actually, he's just one of the better players, because he's a good baserunner, too. He's grown into one of our mainstays. It's fun when you see guys come through the system, because they're ours, so we are a little more proud, sure."
Youkilis is now entrenched as a central figure for these Red Sox, a face of the team much like Johnny Damon, Curt Schilling or Pedro Martinez were in 2004.
While the 2004 Red Sox affectionately labeled themselves the "Idiots" for their wildly light demeanor, Youkilis is a symbol of this team with his grit.
"I never thought that was a great terminology for it," Youkilis said of the 2004 team. "But they were loose, fun guys. You never want to be called an idiot. I know I can be at times about certain things. It's just a different group of guys. We don't all have beards and long hair, and stuff like that."
What they do have is one dynamic cleanup hitter in Youkilis. After finishing third in the American League's Most Valuable Player Award voting last year, Youkilis again was a force this season. He hit .305, scored 99 runs, drilled 27 homers, had 94 RBIs and a career-high on-base percentage of .413.
"You know, even when he was a role player, he doesn't give at-bats away," said Red Sox ace Josh Beckett. "He didn't give at-bats away then, he doesn't give at-bats away now."
The 30-year-old Youkilis is just one of those players who doesn't give an inch when he is on the field. Now, he is back in the postseason, a stage on which he's always thrived. The urgency of each game fits his personality.
"I don't think there's any comfort in the playoffs," Youkilis said. "There's a lot of pressure there to win. It's best of five. It's a little different than best of seven. For us, it's just about going out there and playing the game. I think we've had success just by being a good team and not trying to put too much pressure on ourselves."
Youkilis maintains that the calendar change in October doesn't change anything about how he plays the game.
"For me personally, I don't see this as any different than Game 1 of 162," said Youkilis. "I just go out there and do everything I've done from Spring Training on and have the same attitude. The adrenaline is a little higher in the postseason. You're a little more excited. That seventh inning or eighth inning you're probably not as tired as you are in September. Other than that, it's fun. These games are fun. That's what it's about -- having fun. There's so much meaning to these games and trying to win a World Series."
Despite the increased prominence of Youkilis, he tries not to view his role any differently than back when he was trying to make a name for himself.
"I don't see it as a responsibility," Youkilis said. "I just go out and just play the game. I think people look at it as a responsibility, but if you personally think you're responsible for this team, I don't think that's the right way to go about it. I just go do whatever I can to help this team win. Whatever I can do to help a player on this team to get better that day, I'll do that.
"If you put a lot of responsibility on yourself, you're putting too much added pressure that's not needed. I just go out there and play the game. And hopefully going out there and playing the game the right way and playing hard will allow this team to win."
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.