Here's how the 10 postseason teams were built

The Red Sox and Cubs built two of baseball's best teams in similar fashion. They mostly used homegrown hitters to fortify their lineups and trades and free agents to construct their pitching staffs.
Boston drafted its stellar outfield of Andrew Benintendi, Mookie Betts and Jackie Bradley Jr. and signed Xander Bogaerts and Rafael Devers internationally. Chicago parlayed its 2011-15 first-round picks into Javier Báez, Albert Almora Jr., Kris Bryant, Kyle Schwarber and Ian Happ and found Willson Contreras in Venezuela. The Red Sox's projected playoff rotation and closer all came via trades (Chris Sale, Eduardo Rodriguez, Rick Porcello, Craig Kimbrel) or free agency (David Price), as is true with the Cubs (free agent Jon Lester and trade acquisitions Kyle Hendricks, Cole Hamels, José Quintana and Pedro Strop).
Despite the similarities between Boston and Chicago, there's no set blueprint for putting together a playoff club. The Rockies led all off the postseason clubs with 12 homegrown players on their 25-man roster, while the Athletics had just four on their projected Division Series roster. Oakland topped them all with seven free-agent signings, while the Dodgers have just two. The Brewers landed 15 of their players via trade, the A's got 14 that way, and the Yankees and Cubs each swung deals for 13 of theirs, while Colorado picked up just four players in trades.
Here's a more detailed breakdown of how each of the playoff teams was built, based on their Division Series rosters (projected rosters, in the case of the A's and Cubs):
AMERICAN LEAGUE
A's
Homegrown (Draft + Int'l): 4 (WAR: 16.5)
• Draft: 4 (WAR: 16.5)
• International: 0 (N/A)
Free Agents: 7 (WAR: 5.6)
Trades: 14 (WAR: 25.3)
The four homegrown players on the A's projected roster were among the fewest among postseason teams. They're all products of the Draft, a group highlighted by 2014 first-rounder Matt Chapman, who's emerged as baseball's best defensive third baseman and a franchise cornerstone for the A's, and 2012 comp pick Matt Olson. Together, the duo combined to hit 53 homers and 75 doubles during the regular season. Trades in recent years for players such as AL home run leader Khris Davis (2016 from Brewers), Marcus Semien (2014 from White Sox), Jed Lowrie (2015 from Astros) and Stephen Piscotty (2017 from Cardinals) have helped the A's fill out a potent offense, and the same can be said for the club's elite bullpen trio of Blake Treinen (2017 from Nationals), Jeurys Familia (2018 from Mets) and Fernando Rodney (2018 from Twins). And while season-ending injuries ultimately shelved much of their Opening Day rotation, the A's managed to effectively patch holes with free-agent veterans Brett Anderson, Trevor Cahill and Edwin Jackson and then acquired Mike Fiers from the Tigers in August.
Astros
Homegrown (Draft + Int'l): 11 (WAR: 26.1)
• Draft: 9 (WAR: 18.7)
• International: 2 (WAR: 7.4)
Free Agents: 3 (WAR: 6.6)
Trades: 8 (WAR: 18.2)
Waivers: 2 (WAR: 2.7)
Rule 5 Draft: 1 (WAR: 2.5)
Four of the best players on the defending World Series champions were taken with a No. 1 or 2 overall pick in the Draft: Astros draftees Carlos Correa (No. 1, 2012) and Alex Bregman (No. 2, 2015) and blockbuster trade acquisitions Justin Verlander (No. 2, 2004, Tigers) and Gerrit Cole (No. 1, 2011, Pirates). By contrast, Houston also has a former MVP and a former Cy Young Award winner who vastly exceeded expectations in Jose Altuve, signed for $15,000 out of Venezuela in 2006, and Dallas Keuchel, a seventh-rounder two years later. George Springer, a 2011 first-rounder, also was on hand when Jeff Luhnow took over as GM later that year. In addition to overseeing the Correa and Bregman drafts and making the Verlander and Cole deals, Luhnow made a number of smaller acquisitions that have paid off such as plucking Marwin Gonzalez in the Rule 5 Draft, claiming Collin McHugh off waivers and signing Charlie Morton as a free agent.
Indians
Homegrown (Draft + Int'l): 7 (WAR: 17.9)
• Draft: 5 (WAR: 9.4)
• International: 2 (WAR: 8.1)
Free Agents: 5 (WAR: 4.4)
Trades: 12 (WAR: 29.2)
Waivers: 1 (WAR: -0.1)
The Indians' secured their third straight AL Central title in 2018 with a largely unchanged roster compared to previous years. Homegrown phenoms Francisco Lindor (first round, 2011) and Jose Ramirez (international free agent, '09) are MVP candidates once again and headlined an Indians offense that also featured free-agents signings Edwin Encarnación ('16) and Yonder Alonso ('17). On the mound, trade acquisitions Corey Kluber (2010), Carlos Carrasco ('09) and a combination of Trevor Bauer ('12) and Mike Clevinger ('14) gave the Indians a top-flight rotation, and the club dealt a top prospect for bullpen help for a second time in three years when it landed Brad Hand and Adam Cimber from San Diego at the Trade Deadline and then acquired Josh Donaldson from Toronto the following month.
Red Sox
Homegrown (Draft + Int'l): 10 (WAR: 22.2)
• Draft: 7 (WAR: 17.8)
• International: 2 (WAR: 3.8)
Free Agents: 4 (WAR: 13.2)
Trades: 12 (WAR: 21.5)
With a notable free-agent exception (J.D. Martinez, David Price) in each case, the Red Sox compiled the best record in baseball and won their third straight American League East title with a lineup built around homegrown hitters and a pitching staff assembled through trades. MVP frontrunner Betts was a fifth-round pick in a 2011 Draft that also yielded supplemental first-rounder Bradley, while Benintendi was a 2015 first-rounder and Bogaerts signed for $410,000 out of Aruba in 2009. President of baseball operations David Dombrowski sacrificed top prospects to acquire Sale and Kimbrel, who have starred in Boston. Previous GM Ben Cherington dealt for Rodriguez and Porcello when the Red Sox were rebuilding.

Yankees
Homegrown (Draft + Int'l): 9 (WAR: 23.4)
• Draft: 5 (WAR: 12.4)
• International: 4 (WAR: 11.0)
Free Agents: 3 (WAR: 3.9)
Trades: 13 (WAR: 27.7)
The Yankees' best hitter (2013 first-round choice Aaron Judge) and best pitcher (Luis Severino, signed out of the Dominican Republic for $225,000 in 2011) are homegrown products. Yet for the most part, trades are the backbone of a team that made its third postseason appearance in four years. The Giancarlo Stanton deal was a splashy move that generated a lot of headlines, but GM Brian Cashman also has excelled at making stealth moves for the likes of Aaron Hicks (from the Twins in exchange for John Ryan Murphy), Didi Gregorius (D-backs for Shane Greene), Chad Green (Tigers for Justin Wilson) and J.A. Happ (Blue Jays for Brandon Drury and Billy McKinney). And in a rare year where the Yankees were sellers and not buyers, they grabbed Gleyber Torres in a package from the Cubs for Aroldis Chapman in 2016.
NATIONAL LEAGUE
Braves
Homegrown (Draft + Int'l): 7 (WAR: 21.1)
• Draft: 3 (WAR: 7.3)
• International: 4 (WAR: 13.8)
Free Agents: 6 (WAR: 7.4)
Trades: 11 (WAR: 15.9)
Waivers: 1 (WAR: 0.3)
The Braves' rebuild went into overdrive, getting them back into the postseason for the first time since 2013 well ahead of schedule. The turnaround certainly has some homegrown flavor, with international signees Ronald Acuña Jr. and Ozzie Albies leading the charge and veteran Freddie Freeman the most key draftee, taken way back in the second round of the 2007 Draft. But the best talent acquisition has come via trade, often obtained while still in the Minor Leagues. Former No. 1 overall pick Dansby Swanson, who missed the NLDS due to a torn ligament in his left hand, is the most obvious example, but that list of acquired prospects also includes Mike Foltynewicz, who had made it to the big leagues with the Astros in 2014 but established himself as a Brave in 2015, along with contributors like Rio Ruiz, Touki Toussaint and Max Fried. A few seemingly quiet acquisitions of established big leaguers, like Ender Inciarte (who came with Swanson from the D-backs via trade) and Nick Markakis (free-agent signing) provided the finishing pieces.

Brewers
Homegrown (Draft + Int'l): 4 (WAR: 1.9)
• Draft: 3 (WAR: 2.0)
• International: 1 (WAR: -0.1)
Free Agents: 3 (WAR: 11.2)
Trades: 15 (WAR: 27.9)
Waivers: 3 (WAR: 4.0)
In their first postseason appearance since 2011, the Brewers' roster features more players (18) acquired via a trade or waiver claim than any other playoff team. Christian Yelich, acquired from Miami during the offseason, has been an MVP candidate, while slugger Jesús Aguilar has blossomed into star slugger after being claimed off waivers from the Indians in February. GM David Stearns added a host of upcoming free agents at the Deadline through deals for veteran hitters such as Mike Moustakas (Royals), Jonathan Schoop (Orioles) and Curtis Granderson (Blue Jays), lefty starter Gio González (Nationals) and reliever Joakim Soria, who is part of a dynamic bullpen that includes fellow acquisitions Josh Hader (Astros, '15), Jeremy Jeffress (Rangers, '17) and Corey Knebel (Rangers, '15). Lorenzo Cain, the club's major offseason signing, should also garner some MVP votes after an outstanding season -- his first as part of a 5-year, $80 million deal -- alongside Yelich in the Brewers' outfield.
Cubs
Homegrown (Draft + Int'l): 7 (WAR: 15.5)
• Draft: 6 (WAR: 12.7)
• International: 1 (WAR: 2.8)
Free Agents: 5 (WAR: 11.1)
Trades: 13 (WAR: 17.4)
The Cubs famously and successfully used five consecutive first-round picks on hitters: Baez (2011), Almora (2012), Bryant (2013), Schwarber (2014) and Happ (2015). All are key cogs in Chicago and Baez may be the National League MVP, but the only other homegrown players on the postseason roster were Contreras (signed for $850,000 out of Venezuela in 2009) and David Bote (an 18th-rounder in 2012). The Cubs were vying for their second championship in three years and fourth straight National League Championship Series appearance with a pitching staff comprised solely of trade acquisitions (Hendricks, Hamels, Strop, Quintana) and free-agent signings (Lester, Steve Cishek) made by president of baseball operations Theo Epstein and GM Jed Hoyer. They also went outside the organization to sign Ben Zobrist and deal for Anthony Rizzo.
Dodgers
Homegrown (Draft + Int'l): 11 (WAR: 23.7)
• Draft: 6 (WAR: 16.7)
• International: 5 (WAR: 7.0)
Free Agents: 2 (WAR: 8.7)
Trades: 12 (WAR: 24.9)
Though the Dodgers had baseball's largest payroll each year from 2014-17 and rank third among postseason teams in 2018, they are the most homegrown postseason participant besides the Rockies. Clayton Kershaw (2006) and Walker Buehler (2015) were first-round selections, while Ross Stripling (fifth round, 2012) and Cody Bellinger (fourth round, 2013) were later-round steals. Los Angeles leads all playoff clubs with five international signees, including Yasiel Puig ($42 million contract out of Cuba in 2012), Hyun Jin Ryu ($36 million contract, Korea, 2012) and Kenley Jansen ($85,000 as a catcher, Curacao, 2004). The Dodgers have fewer free agents than anyone, though both Justin Turner and Max Muncy have made bigger impacts that expected. President of baseball operations Andrew Friedman and GM Farhan Zaidi have filled out the lineup with astute trades for Manny Machado, Chris Taylor, Yasmani Grandal and Kiké Hernández.
Rockies
Homegrown (Draft + Int'l): 12 (WAR: 29.4)
• Draft: 11 (WAR: 28.1)
• International: 1 (WAR: 1.3)
Free Agents: 6 (WAR: 0.8)
Trades: 4 (WAR: 11.1)
Waivers: 3 (WAR: 2.2)
No playoff team relied on its homegrown nucleus more than the Rockies, who made their second straight playoff appearance. Their three best hitters are all products of the Draft (2011 supplemental first-rounder Trevor Story, 2009 second-rounder Nolan Arenado, 2008 second-rounder Charlie Blackmon), as are four of their top six pitchers (2014 first-rounder Kyle Freeland, 2011 first-rounder Tyler Anderson, 2013 first-rounder Jon Gray, 2012 15th-rounder Scott Oberg). Colorado has by far the fewest trade pickups (four) of any of the postseason participants, though Germán Márquez and DJ LeMahieu have been essential after coming over in one-sided deals. Free agency hasn't been as kind to the Rockies, as they spent roughly $52 million this year on five guys who combined for -0.4 WAR, but Adam Ottavino is the best waiver claimee to pitch in this year's playoffs.