Without changing anything, the San Diego Padres were likely to improve next season. The entire lineup underperformed in 2014, and the team’s poor season totals masked some improvement in the past few months.

Rather than waiting to see how much better the team would be if some of his players had more typical seasons, however, A.J. Preller, San Diego’s general manager, reshaped the roster, trading a huge chunk of the farm system for Justin Upton, Matt Kemp, Wil Myers and Derek Norris.

Suddenly, a team of little-known underperformers had a group of household names with excellent credentials: five All-Star appearances, two Gold Gloves, four Silver Sluggers, a rookie of the year and two top-10 finishers in MVP award voting.

The Padres won the headline war, and excited their fan base, but it will take more than next season to judge the flurry of activity because of the potential of the prospects who were traded.

The more immediate issue is whether San Diego acquired as talented a group as many seem to think. Each player is capable of great things, and will make the Padres better next season, but there are reasons they were available in trades.

For Kemp, health is a concern. During the completion of the trade with the Los Angeles Dodgers, in which the Padres received $32 million to offset the $107 million remaining on his contract, he was found to have arthritis in his hips. A host of other injuries caused Kemp to miss 56 games in 2012 and 89 games in 2013. Any additional health worries are enough to question whether Kemp can ever return to his form in 2011, when he was probably the best player in the National League.

Kemp was worth 8.6 Wins Above Replacement in 2011, according to Baseball-Reference. Since then, his WAR was just under four for two seasons and below two for one season. That represents an upgrade for San Diego, but Kemp is entering his 30s and is no longer the dynamic wunderkind who burst onto the scene for the Dodgers in 2006. A permanent move to left field might help protect his body and reduce some of the damage his below-average play in center caused. The $75 million the team will pay Kemp is the largest financial commitment in Padres history, so finding a way to keep him on the field is vital.

Upton, also an outfielder, is a lower risk than Kemp because of his sterling health history. But Upton also produced what is looking more and more like his career season in 2011: a 6.1 WAR to go with 31 home runs and 21 stolen bases. He finished fourth in the National League MVP voting (two places below Kemp) and seemed on his way to being one of the best players in the game.

Upton has been an effective player the past three seasons, worth an average of 2.7 WAR, but his reputation has outpaced his production.

The good news is that Upton, 27, is at an age when many players reach their physical peak. And his remarkable power for a player of his frame makes Petco Park, which has humbled many so-called sluggers, less daunting. Last season with Atlanta, Upton hit 17 home runs that traveled 400 feet or more, according to ESPN’s home run tracker, including a 477-footer off Jenrry Mejia of the New York Mets that will not soon be forgotten.

Myers, the 2013 AL rookie of the year, was such a coveted minor leaguer that Tampa Bay acquired him by trading James Shields, a No.1 starter. He played in just 87 games in 2014 and regressed in virtually every category. No one would suggest that last season was indicative of Myers’ talent, but his maturity was questioned. Myers, 24, once viewed as a building block, was instead shipped out for even younger players.

Norris, one of the leaders of the surprising Oakland Athletics last season, rode a strong first half to an All-Star appearance. But as is common with catchers, he was not nearly as effective in the second half, with his on-base plus slugging percentage dropping to .638 from .879 before the All-Star break.

Norris, 25, can play some first base to lessen the wear and tear on him, and he will most likely be a San Diego fan favorite as he was in Oakland.

Other teams have tried drastic face-lifts like this with mixed results. If the players fit well, stay healthy and play to their potential, San Diego could be a real force.

But by mortgaging the team’s future to make the deals, the Padres will have a hard time mounting a threat in a division dominated by the San Francisco Giants and the Dodgers.

Preller has made a name for himself, and acquired a lot of name players, but the jury will be out on these moves for years to come.