Black, who pitched 15 seasons in the majors, said he sometimes woke this winter to find a text message sent by Preller at 4:30 a.m. The work ethic impressed him, but he was struck even more by Preller’s feel for the game — for players and for competition. Preller graduated from Cornell in 1999 and did not play professionally, but showed a hunger to win now, rather than wait on prospects for a distant payoff.

“He was looking to rebuild the offense’s identity and the organization’s identity,” said Upton, who launched a homer off the center-field backdrop on Wednesday. “He wanted to build a contender and he thought that I was a piece of that. When he called and told me it was going to be a good year and we weren’t done making moves, and we wanted to still make the team better, I was on board.”

Upton will play left field and Kemp will play right. Myers, the 2013 American League Rookie of the Year for Tampa Bay, will play center. He has started just six games there in the majors, but he played 100 games in center in the minors and called it his best position.

The motivations of the new outfielders are clear. Upton will be just 28 when he becomes a free agent for the first time, after a solid career for Arizona and Atlanta. Kemp, once a cornerstone of the Dodgers, was shipped to a rival to make room for a rookie, Joc Pederson.

Then there is Myers, who learned of his trade from a Rays pitcher, Jake Odorizzi, who saw a rumor in a news report. Myers had hit just .222 with six homers in 87 games, but never felt strong after jamming his left wrist in the first week of the season. Then he broke his right one, sidelining him for months. He went from a building block to the trading block, and said he could hardly believe it.

“It was the first bad year of my career — with injuries,” Myers said. “I’m not worried about the fact people say, ‘Well, he’s washed up.’ I’m 24. I didn’t lose talent. I didn’t lose my baseball skills. I still know how to play; I still know how to hit. I’m finally healthy again, and I’m excited to rebound and prove everybody wrong.”

Myers has never played at Petco Park, a notorious place for power hitters at night, but Kemp and Upton have succeeded there. Kemp has a .495 career slugging percentage in San Diego, and no visitor has hit more home runs at Petco than Upton, who has 10.