He just doesn't think Sveum is the right guy to help all those prospects become successful major leaguers.
The Cubs fired Sveum on Monday after finishing last in the NL Central for the first time in seven years, ending a two-year run that produced more losses than any other stretch in the team's cursed history.
"It's absolutely imperative that we create the best environment possible for young players to come up here, continue to learn, continue to develop and thrive at the big league level and win, ultimately," Epstein said during an afternoon news conference. "And that's not an easy thing to do.
"A big part of the reason why we're here today is because we took a good hard look at that and we decided that we needed to try to get it right before they come up."
Sveum was among Epstein's first hires after the executive came over from the Boston Red Sox in 2011. He had little experience as a manager when he agreed to take the job, and he knew the Cubs were at the very beginning of a top-to-bottom overhaul that they hoped would transform them into perennial contenders.
He just thought he would get more time to make it work.
"You come in and you get a job like this and you want to see it through and so you're very disappointed you didn't get to really get anything started," Sveum said in a parking lot outside Wrigley Field.
Sveum, who had one year left on his contract, said he thought he was fine before Epstein said during Chicago's trip to Milwaukee in mid-September that the manager was being evaluated.
"That was about when things got started," Sveum said.
While praising Sveum's time in Chicago and his growth with the Cubs, Epstein disputed the notion that the manager was blindsided by the move. He said Sveum had been aware of some concern in the front office for some time.
"We met shortly after the All-Star break, a long meeting, a long, difficult, brutally honest meeting where we explained the areas where we felt like we needed to see improvement," Epstein said. "We told him, 'We are meeting with you because for the first time there are some concerns about whether you're the long-term guy and you deserve to hear that feedback from us and you deserve the second half of the season to work on those areas.'"
Epstein said he also talked to Sveum before he made his comments in Milwaukee and let him know there were still discussions going on in the front office about whether he would be retained for next season.
In the end, they decided to make a change.
Chicago went 61-101 in Sveum's first season, and then stumbled down the stretch in 2013 while some of its best players were traded away for prospects. The Cubs dropped 41 of their final 59 games, including six of their final seven, finishing with a 66-96 record.
But it looks as if wins and losses were not a major factor in Sveum's dismissal. Shortstop Starlin Castro and first baseman Anthony Rizzo, two key young players who have long-term contracts, each took a step back this year. Pitcher Jeff Samardzija also had an uneven season.
Talented prospects such as Javier Baez, Jorge Soler, Albert Almora and Kris Bryant are on the way, and Epstein made it clear that providing the right atmosphere for those players was a key issue when it came to Sveum's dismissal.
"Not in all cases, there were some good results this year, some young players emerged, but there were other young players who didn't continue to develop this year," Epstein said. "That's a collective issue, but it's my responsibility to get it right."
Sveum, who played a role in the development of sluggers Prince Fielder and Ryan Braun when he was a coach in Milwaukee, said he was looking forward to managing those prospects when they got to the majors.
"Being here when all these players got here, that's the biggest disappointment, if anything," said Sveum, who isn't sure what he's going to do next season. "You didn't get a chance to see it through."
Epstein said previous managing experience will be a point of emphasis in their search, and he plans to complete the process before the general manager meetings in early November.
Sveum's dismissal likely will ramp up speculation surrounding the status of Yankees manager Joe Girardi, a Peoria, Ill., native who played college ball at nearby Northwestern. The former Cubs catcher just completed the final season of his contract with New York, but he downplayed his connection to Chicago over the weekend.
"There's not as much there as there used to be," Girardi said.
With the Cubs focusing on the future and dealing anyone with trade value in an effort to build the farm system, losses have been piling up at a staggering rate even for a franchise that last won a championship in 1908. The Cubs have dropped at least 91 games in three straight seasons for the first time, and they appear to be at least a year or two from making any jump in the win column.
Despite those problems and Sveum's short stint in charge, Epstein doesn't think he will have to sell the manager opening to any potential candidate.
"We know exactly what we're looking for and I think we're going to find it," he said.
AP Sports Writer Schuyler Dixon in Houston contributed to this report.
Jay Cohen can be reached at http://www.twitter.com/jcohenap