Beckett, who the year before had been the Marlins' first-round draft pick (second overall behind Josh Hamilton), was only 19 and not even a year removed from pitching in high school, but he was ready to make a statement.
"From the get-go, he came to camp and he was different," said Lowell, who was already an established major league third baseman on that Marlins club. "Josh wanted to prove that he was not only the best pitcher on the team, he wanted to prove he was the best player on the field. I'll always take an aggressive guy like that rather than a passive guy."
Several Marlins veterans lobbied then-manager John Boles that spring to place Beckett on the Opening Day roster. Boles knew Beckett was talented but still raw and decided that more experience at the minor league level, the kind that would let his talent flourish and not become stifled, was best for the club's phenom.
"Of course, we were never going to do that because there was no need to rush him,'' said Boles, now a special assistant with Seattle. "Most times when you draft a pitcher that high, he comes in and, as a club, you say, 'He needs to improve his breaking pitch, or he needs better command.' You basically end up picking a guy apart. With Josh, we all knew he was going to be our No. 1 and he was going to pitch in World Series games. If someone came up to me and said, 'OK, it's Game 7 of the World Series, who do you want?' I have a hard time coming up with anyone other than Josh Beckett."
Fast-forward to 2009 and Beckett's talent has made him one of the game's top pitchers. He is still trying to win his first Cy Young Award (he finished second to CC Sabathia in 2007), but he has something almost any Cy Young winner would trade for in an instant.
Beckett is a two-time World Series champion, and the Boston Red Sox would like to see him add a third title this fall. When he arrived in Boston with Lowell in a 2006 trade with the Marlins, the Red Sox immediately pulled him aside and told him of their expectations for him.
"When he first got here, we told him, 'You're the guy,'" manager Terry Francona said. "We said, 'You're the No. 1 guy.' He loves having that attached to him. He loves the responsibility that comes with it. Josh likes the bar to be as high as possible."
Said Lowell: "It probably wasn't fair to expect him to pitch at the level they wanted. But that's him. He exceeds what anyone thinks of him."
Beckett, who won't turn 30 until May, is most responsible for the bar's being set as high as it has been. In his second full season in the majors, in 2003, Beckett took on the responsibility with the Marlins when it mattered most. Florida surprised most everyone in baseball by reaching the postseason as the National League's wild-card representative.
It meant opening the playoffs against the Barry Bonds-led San Francisco Giants, a club that won an NL-best 100 games that year. The Marlins dispatched the big, bad Giants in four games in the first round.
Next up were the perpetual fan favorites, the Chicago Cubs, in the NLCS. The Cubs took a commanding 3-1 lead in the best-of-seven series and were prepared to snag their first pennant since 1945 on a steamy Miami October evening. But Beckett was too much of an obstacle, and the Cubs lost meekly in Game 5 as he pounded his fastballs, sliders and curveballs past baffled Chicago hitters.
It was a complete-game 4-0 victory, one in which Beckett allowed just two hits. Most amazing, the Marlins never even called to the bullpen to have a reliever warm up.
"He was great all season, but from that night forward, he's been a different guy," said Red Sox shortstop Alex Gonzalez, who was the Marlins' shortstop that season. "He's a huge headache for other teams. He can go all nine [innings] on any given night and be completely consistent and dominant throughout the game. He doesn't have to really adjust to hitters; they have to adjust to him."
The Marlins won Game 6 in Chicago in the notorious Steve Bartman game. The next night, the Marlins closed out the Cubs with Beckett, on just two days' rest, pitching four innings of relief, allowing just one hit and slamming the door on the Cubs' hopes.
Florida went into the World Series as a heavy underdog against the New York Yankees. Beckett pitched Game 3 but lost to the Yankees, who took a 2-1 series lead. The Marlins came back to win the next two as the series returned to Yankee Stadium.
The talk leading into Game 6 was whether the Marlins would pitch Mark Redman and hold Beckett back a day to pitch on his regular rest in a possible Game 7 or push Beckett up a day and have him start on three days rest.
"Why would I hold back a thoroughbred like Josh?" then-Florida manager Jack McKeon asked at the time. "What if we lose Game 6 and then we're down to one game? Anything can happen at that point. There's no reason not to pitch Josh in Game 6."
All Beckett did was clamp down on a mighty Yankees lineup that featured Derek Jeter, Jason Giambi, Jorge Posada, Hideki Matsui, Bernie Williams and Alfonso Soriano. Beckett's final pitching line that night said it all: Nine innings, two hits, no runs. Beckett was voted World Series MVP.
"The '03 playoffs are still like a blur," Beckett said. "It all happened so fast. We were all so young and just having so much fun. I don't think any of us fully realized what we were accomplishing while it was happening. We were playing like we had nothing to lose."
That loss in Game 3 of the 2003 World Series is the last time Beckett has lost a postseason game. His six-game postseason winning streak is just two behind Orlando "El Duque" Hernandez's major league record for starting pitchers.
The Red Sox certainly were taking note of what Beckett was doing that fall. He did something no Red Sox club had been able to do in the previous 85 years: slay the mighty Yankees when it mattered most.
Boston gave up a lot to secure Beckett's services. Included in the package of four players the Sox sent to Florida were minor league phenoms Hanley Ramirez, who has turned into one of the NL's best players, and pitcher Anibal Sanchez, who has thrown a no-hitter for the Marlins.
"Best trade the Boston Red Sox have made since I've been here," designated hitter David Ortiz said.
There's a comment almost universally repeated by the players who have had the most success in October. They all maintain the same philosophy and mindset: The game seems slower to them.
John Smoltz -- who, along with Andy Pettitte, leads baseball's winningest postseason pitchers with 13 W's -- has said the game almost feels as if it's in slow motion when he's on the mound in October. Dave Stewart, who won 10 postseason games, has repeated the same thought.
"It's something that's inside of certain guys," said former Cleveland manager Eric Wedge. "It's an intangible. Some guys get all geeked up when they get into October and forget what got them there. The ones who really stand out are the ones who stay on the same level. I think it's internal. It's their heartbeat. The great ones are able to stay the same and let the other guys get all amped up. Some players just play with more confidence in October."
Beckett talks about it in a slightly different way, but with the same idea.
"We have a psychologist who tells us to act like we're riding in a Mercedes," Beckett said. "He wants us to get out of the big 4x4. If you're in one of those huge 4x4 trucks, you can pretty much crush or run over anything. But that's not the way to make things happen on the mound. You want to be in the Mercedes. You might be going 90, but it feels like you're going 50. In a truck, you feel all the bumps and potholes. That's not the way you want to pitch. You want to be intense, but relax and feel smooth."
Beckett also maintains that his father's advice after his first season in the minors is his mantra.
"I was with my dad that first winter and he said, 'Don't ever let people make excuses for you,'" Beckett said. "I go back to that one statement all the time. I don't want anyone to say 'He could have done better if …' or 'If this hadn't happened, he probably would have had a better result.' I don't want to be that guy."
All the philosophy aside, at his core, Beckett is a worker. He prepares every day of every week for his starting assignments.
"If he pitches eight innings on a Thursday, Friday is not a kick-back day for him," Francona said. "He works hard all the time, all year to get himself ready for each and every one of his starts, especially the ones that come at this time of the year. I think he loves the biggest stage."
Not surprisingly, at least not to those who know Beckett best, he's there once again.
Pedro Gomez, who covers the Red Sox for ESPNBoston.com, is a reporter for ESPN.