The list of available players could change considerably in the weeks ahead as teams reassess their situations.
For now, however, here are some of the players opposing teams have been scouting in recent weeks and why they might be available:
C.C. Sabathia, Indians. Having failed to sign Sabathia to an extension during the offseason, the Indians might be willing to part with the free-agent-to-be as Sabathia would almost certainly be the top starter on the market were the Indians to make him available. With Jake Westbrook out for the year, Cleveland's 2008 chances have slipped, and with another starter headed for free agency this winter in Paul Byrd, the Indians could get a significant return for their two pending free agents.
Ken Griffey Jr., Reds. Now that he's reached 600 career homers, the Reds will listen to offers, but without a clear fit among the current contenders it's not a given Griffey, who has a full no-trade clause, will be going anywhere. Teams have also been scouting Adam Dunn in case the Reds decide to make the outfielder/first baseman available.
Matt Holliday, Rockies. The defending National League champions are in last place with the worst record in the league. Holliday is one of the best players in the game and is looking for a long-term extension. The Rockies are considering that option. Trading him is another.
Holliday is making $9.5 million this year and will be paid $13.5 million for 2009, then he can become a free agent. A player of Holliday's caliber who isn't heading into free agency for another year and a half will attract plenty of attention if the Rockies decide to go that route.
Xavier Nady/Jason Bay, Pirates. Nady appears to be drawing more interest but both outfielders are having fine seasons. The Pirates aren't actively shopping either at the moment but other teams expect one or both to go for prospects this summer. Bay is signed through 2009 with $5.75 million due this season and $7.5 million next year. Nady avoided arbitration by signing a one-year, $3.35 million contract.
Greg Maddux, Padres. The Padres are nine games under .500 and unless things turn around, they may start looking to the future. One step would be to deal Maddux to a contender, with the Braves an obvious fit.
Brian Giles, Padres. The veteran outfielder is having a good year and doesn't figure in San Diego's long-term plans. Giles has a $9 million option (or a $3 million buyout) for 2009 and would be an excellent fit for a club needing a left-handed-hitting corner outfielder.
Milton Bradley, Rangers. Having a superb year and with an attractive contract -- $5.25 million -- Bradley would bring instant offense to any contender. The Rangers aren't out of the race by any means, but if they decide to become sellers, Bradley, a potential free agent this winter, will attract attention.
Gerald Laird, Rangers. Catchers are hard to come by these days and Laird is young, inexpensive and having a good year. Just the kind of talent who would likely bring a nice return in a trade. And the Rangers can afford to consider trading Laird since they have Jarrod Saltalamacchia on the roster.
Bad news for the rest of the league: Vladimir Guerrero is starting to heat up.
The Angels right fielder came into the season with a .325 career batting average but struggled early, batting only .219 in May. But he's turned it on in June, hitting .458 (11-for-24 through Wednesday's game) and his on-base percentage for the month is .533, more than double than it was in May (.260).
"He's always been a great bad-ball hitter, but I think pitchers have been using that against him more effectively," a scout said. "He's changed his stance a little bit and walking more."
After drawing just five walks in 25 games during May, Guerrero already has received four free passes in six June games.
Atlanta's Brian McCann and Geovany Soto of the Cubs are having All-Star-caliber seasons, but another young catcher was the choice of a veteran scout when asked which catcher he'd pick if he were drafting a team.
"Dioner Navarro," the scout said. "Switch-hitter, punishes mistake pitches as well as just about anybody. He's only [24 years old] and just keeps getting better and better."
Navarro's .338 batting average would lead the American League and be the fourth highest in baseball had he had enough at-bats to qualify. He's 32 plate appearances shy due to a stint on the 15-day disabled list in April.
Navarro, who has nine hits in his last 23 at-bats, is batting .310 (104-for-336) with 11 homers and 56 RBIs since last year's All-Star break. His on-base-plus-slugging percentage after the break last season was .815. This year it's .826.
Chase Utley or Chipper Jones? Here's one scout's point of view.
"You can't go wrong with either one, but I like Utley a little bit better," he said. "He will hit [for] extra bases. He will steal you a base. Chipper used to be able to steal a base, but not so much now. They are so close. But at this stage of their careers, I just like Utley a little more."
Don't underestimate the impact outfielder Shane Victorino has on the Phillies, a scout said.
"This guy is a spark. He gets on base, steals a base. He gives you something to worry about," the scout said. "With [Jimmy] Rollins and him at the top of the order, they get things rolling. He's a really good, under-the-radar player. Just think, a couple of years ago, he was a fourth outfielder."
Astros GM Ed Wade held a 10-minute, closed door meeting with the team prior to batting practice on Tuesday.
"I'm not going to talk about the meeting," Wade said. "With all due respect, we had the team meeting, talked about some things, clarified some things and got ready for the game tonight. If I wanted the media to be in the meeting, I would have invited them in."
After going 17-11 in May, the Astros lost five of their first seven games in June.
Houston manager Cecil Cooper, who did not address the team during the meeting, described it as a mechanism to "reconfirm what we all committed to in Spring Training -- being focused on winning and that kind of thing."
When Florida's Luis Gonzalez hit his 350th career home run last week, he became only the seventh player in Major League history to hit at least 350 homers and 575 doubles in his career. The others: Stan Musial, Carl Yastrzemski, Hank Aaron, Cal Ripken Jr., Barry Bonds and Rafael Palmeiro.
Gonzalez's historic milestone was overshadowed as Boston's Manny Ramirez hit his 500th career home run, and Cincinnati's Ken Griffey Jr., who hit No. 600.
"Mine wasn't quite as dramatic," Gonzalez said.
Dayan Viciedo, the 19-year-old third baseman who escaped Cuba and is currently awaiting a decision by MLB on whether he is a free agent or subject to next year's First-Year Player Draft, is on the radar of most teams. The Astros, Yankees, Cardinals, Angels, Mets and Pirates are among the teams known to be considering Viciedo.
Viciedo is staying with relatives in Miami while his agent, Jaime Torres, is working with MLB and the players association in an attempt to clarify Viciedo's status.
Jim Molony is a reporter for MLB.com. MLB.com reporters contributed to this report. This story was not subject to the approval of Major League Baseball or its clubs.