There are many seasons within each baseball season. Hope springs eternal in April, when each team entertains dreams of a pennant; by July, contenders are beginning to emerge; in September, pennant races dominate the landscape.

The importance of the first two months lies in determining who will contend and who will begin making early plans for next year. As teams sort themselves into front-runners and also-rans, they also split into buyers and sellers in baseball’s ever-changing market. A team off to a promising start in April can join the “buyer” line, while a team that bombs in the first month is normally relegated to the much longer “seller” line. In this light, it’s never too early to start wondering who will be available at the trade deadline.

Last April, for example, the Kansas City Royals were coming off an improbable 83-79 record and envisioning a wild card berth. But they finished the month at 7-15, wrapped up May at 18-31, and spent June wondering where to trade Carlos Beltran. The superstar center fielder ended up in Houston, where he led the Astros on a late run at the wild card.

Coming off their first playoff series win, the Astros have high hopes for the 2005 season. But with Beltran gone to New York, Lance Berkman out until May with an ACL injury, and Jeff Kent wearing Dodger blue, the team’s prospects look bleak. Those three players were the team’s best hitters last season, combining for 80 of the Astros’ 187 home runs. Meanwhile, Roger Clemens is signed to a one-year, $18 million contract, and second baseman Craig Biggio and catcher Brad Ausmus are in the final years of the their contracts. If April is a bust, the Astros may decide that it’s time get something in return for their best players before it’s too late.

Similarly, the Chicago White Sox are an aging team that seems set up to fail. The Sox finished second in the AL Central for the third straight season in 2004, but rather than make a concerted push for the next level, the Sox replaced the departed Magglio Ordonez and Carlos Lee with the uninspiring Jermaine Dye and A.J. Pierzynski. By the end of April, the Sox will likely be treading water; by September, they might be swimming upstream.

With a summer of disappointment on the horizon, the White Sox may look to deal first baseman Paul Konerko, who is making $8.75 million this year in the final year of his contract. Likewise, veterans Frank Thomas, Carl Everett, Jose Contreras, and Orlando Hernandez aren’t likely to be around for the next competitive White Sox team. If the Sox don’t get off to a hot start this month, GM Kenny Williams may be forced to deal any or all of them to get value before they depart.

But the team most in need of a hot start is the San Diego Padres. General Manager Kevin Towers has put together a very good team, one that should definitely contend for the N.L. West crown. But even good teams can get off to bad starts, and with an underwhelming pitching staff, the Padres could be one of them. If the Dodgers or Giants open up a substantial lead in the division, the Padres could find themselves on the outside looking in with several big contracts limiting the team’s options for the future.

The Padres’ course of action isn’t as clear as Houston’s or Chicago’s. The two contracts the Padres would do best to unload are those of Ryan Klesko and Phil Nevin, who are owed a combined $19 million this year and $20 million in 2006. Klesko and Nevin are both 34-year-olds, they’ve both seen their power numbers decline in recent seasons, and the Padres can’t seem to decide whom to play at first base and whom to play in the outfield – neither plays either position especially well.

Meanwhile, the Padres are in danger of losing Ramon Hernandez and Brian Giles as free agents after this season. Hernandez, a promising 29-year-old catcher, has shown improvement in each of the last three seasons. Giles is remarkably similar to Klesko and Nevin in age and defensive prowess, but his record of top offensive performance is longer and better.

If the Padres find themselves falling behind the pace in May, they’ll have to decide what they want to do: Deal Giles and try to compete again in 2006 with Klesko and Nevin, or try to deal Klesko or Nevin – knowing they’ll likely have to cover large chunks of owed money in the process – and hope to save enough cash to sign either Hernandez or Giles next winter.

The problems potentially facing the Astros, White Sox, and Padres would all be solved by a hot start to the season, and a prolonged stay in the buyer’s market rather than the seller’s. But stumbling out of the starting blocks while division rivals fly off to the races could force any of these teams to make some tough choices between hoping for a improbable September run this year or planning for the future.

Mr. Click writes for Baseball Prospectus. For more state-of-the-art statistical content, please visit www.baseballprospectus.com.