Typically, having the right pieces to fill immediate needs comes down to having prospects to offer potential trade partners. While building a farm system is essential for long-term success in that it can feed homegrown players to the big leagues, it's also important so that contending teams have trading chips to use at this time of year.
Some teams currently in contention are better equipped than others to be active between now and the July 31 non-waiver Deadline, especially since most of the sellers in the market figure to be looking for close-to-big-league-ready talent.
With many teams still very much in a race, here's a look at which ones are in the best position to get what they need for the stretch run.
Yankees: New York's challenge will be that the talent at the top of its system -- pitchers Manny Banuelos and Dellin Betances and catcher Austin Romine -- have been hurt or have struggled. There's talent in the lower ranks, namely catcher Gary Sanchez and outfielder Mason Williams, if a team is willing to take on high-end talent that will take longer to develop.
Orioles: It's difficult to imagine Baltimore dealing either of its top two prospects in shortstop Manny Machado or pitcher Dylan Bundy. Middle infielder Jonathan Schoop is their other Top 100 prospect, currently in Double-A.
Rays: Tampa Bay has five prospects in MLB.com's Top 100. Right-hander Chris Archer has already contributed at the big league level, making two starts. Shortstop Hak-Ju Lee is in Double-A. Most of the rest of the Rays' young talent is a little further away.
White Sox: While Chicago's system has been much maligned in recent years, it should be noted that much of the White Sox's current 25-man roster is homegrown.
Indians: A year ago, Cleveland went all-out in trading with Colorado for Ubaldo Jimenez. That deal raided the cupboard quite a bit. What talent remains is far away from the big leagues, so don't expect the kind of blockbuster the Indians pulled off a year ago.
Tigers: Detroit made more noise in the free-agent market than it's likely to make this trade season. The Tigers have a few arms at the upper levels, with Jacob Turner, Andy Oliver and Casey Crosby in Triple-A.
Rangers: Texas gave up two Minor League pitchers last year to get Mike Adams from the Padres and there's still talent to choose from in a deep farm system. Eight of the Rangers' Top 10 are in Double-A or higher.
Angels: Like the Tigers, the Angels did most of their work in the offseason via free agency. Shortstop Jean Segura is their lone Top 100 prospect in the Minors, as right-hander Garrett Richards is in the big leagues. Beyond that, there isn't much in the way of impact talent.
Nationals: Hasn't the Nats' farm system done enough, providing high-octane talent to carry them into first place in the National League East? There are no impact players remaining who'd fetch a lot on the trade market, but there is some talent in Double-A that could draw some interest.
Braves: Atlanta managed to get Michael Bourn without giving up any of its upper-tier prospects a year ago. The Braves dealt two pitchers in that deal with Houston and they still have some pitching depth if they decide to go shopping again.
Mets: A year ago, the Mets were sellers and netted right-hander Zack Wheeler from the Giants. Now they're hanging around the NL East lead and could use some of the pitching they've built -- Wheeler, Matt Harvey and Jeurys Familia are the organization's top three prospects -- to fetch help, if they're not used to pitch in New York.
Pirates: It's difficult to envision Pittsburgh dealing either of its top two pitching prospects in Jameson Taillon and Gerrit Cole, but they do have some depth in terms of just-about-ready arms to draw from as they try to stay atop the NL Central.
Reds: The system was stripped a bit when they acquired Mat Latos from the Padres during the offseason, so there isn't much to deal from. There is some talent on their Double-A team in Pensacola, so look there for any potential deal fodder.
Cardinals: The Cards have one of the most improved farm systems in baseball with some legitimate prospects at just about every level. How much they are willing to raid it remains to be seen, but they have some options from which to choose.
Dodgers: The strength of the Dodgers' system is pitching and teams are often looking for arms at Deadline time. Eight of Los Angeles' Top 10 prospects are pitchers.
Giants: The Giants sent Wheeler to the Mets to get Carlos Beltran last July and that didn't go so well. This time, they might have more depth in hitters, with eight of their top 10 being position players.