How the 10 playoff teams were built

MLBPipeline.com is breaking down how each of the playoff teams was built, looking at the composition of projected Division Series rosters.

There's no easy formula for assembling a winner. Just look at the World Series champions from this decade so far.

The Giants parlayed several astute first-round picks into titles in 2010, 2012 and 2014. The Cardinals won it all in 2011 thanks to a farm system that provided most of their big league roster either directly with homegrown players or indirectly via trades. The Red Sox sandwiched a 2013 World Series victory between last-place finishes, thanks in large part to some prescient mid-level free-agent signings.

This year's playoff teams also were built in a variety of ways.

How the postseason teams were built

The most homegrown postseason club is the Mets, who signed and developed 15 members of their projected Division Series roster. They found key contributors with Draft picks in the early rounds, including David Wright (first round supplemental, 2001), Matt Harvey (first, 2010) and Michael Conforto (first, 2014), as well as in later rounds, such as Lucas Duda (seventh, 2007) and Jacob deGrom (ninth, 2010). New York also topped all teams with five international signees, most notably Jeurys Familia and Wilmer Flores from the same class in 2007.

While the Cardinals NLDS roster is still very much up in the air, St. Louis figures to have 14 or 15, all of whom came from the Draft to lead the playoff teams in that category. Their crop of draftees extends all the way back to 2000, when Yadier Molina was a fourth-rounder, and runs through 2012, when Michael Wacha (19th overall) and Stephen Piscotty (36th) lasted longer than they should have. St. Louis had one of the best drafts in recent years in 2009, when it got Shelby Miller (first round) and Joe Kelly (third) for use in later trades for Jason Heyward and John Lackey and unearthed Matt Carpenter (13th), and Trevor Rosenthal (21st) in the deeper rounds.

Tweet from @MLBPipeline: With @MLB Division Series rosters now set, a look at how the 10 #postseason teams were built: http://t.co/PU3gmrbusV pic.twitter.com/MTHhslKOHx

On the other end of the spectrum, the Cubs have the fewest homegrown players with five but make up for it by topping all clubs with 15 acquired via trades. Chicago dealt for Anthony Rizzo and Jake Arrieta when they were struggling big leaguers and watched them develop into superstars, and brought Addison Russell to Wrigley Field at age 21 less than a year after acquiring him. Since switching gears from rebuilding to competing in the last year, they have traded for veterans such as Miguel Montero, Dexter Fowler and Fernando Rodney.

Video: MLB.com looks at the makeup of the 2015 Cubs

Four other clubs put together the majority of their postseason rosters with trades: the Blue Jays, with 14 acquisitions, and the Dodgers, Pirates and Rangers with 13 each. Toronto made a blockbuster deal for Josh Donaldson last offseason, and then made two more in July to add Troy Tulowitzki and David Price.

Los Angeles' two best players were a free agent (Zack Greinke) and a draftee (Clayton Kershaw), but they also swapped for five of their eight lineup regulars, including Andre Ethier, Adrian Gonzalez and Yasmani Grandal. Pittsburgh originally signed its three most important players (Andrew McCutchen, Starling Marte, Gerrit Cole) and complemented them with deals for the likes of Josh Harrison, Mark Melancon, Francisco Cervelli and J.A. Happ. Texas used its deep farm system to trade for Yovani Gallardo, Cole Hamels, Jake Diekman and Sam Dyson this year alone.

In an upset, the team that has the most free agents on its roster is the Royals with seven, though the combined worth of their contracts is just $59.9 million and they're all bargain-bin values such as Kendrys Morales, Edinson Volquez and Chris Young. Kansas City is also the third-most homegrown club, originally signing 11 members of its roster. It spent first-round picks on Alex Gordon, Mike Moustakas and Eric Hosmer, and finding Salvador Perez, Kelvin Herrera and Yordano Ventura on the international market for a combined $113,000.

Video: MLB.com looks at the makeup of the 2015 Yankees

The Yankees would have had the most free agents with eight if C.C. Sabathia ($191 million contract) hadn't checked into alcohol rehab and Mark Teixeira ($180 million) hadn't gone down with a stress fracture in his leg. New York still has six free agents, including $319 million worth of deals for Brian McCann, Jacoby Ellsbury, Carlos Beltran and Andrew Miller (not to mention another $155 million for Masahiro Tanaka, who technically counts as an international signee). To be fair, the Yankees also have signed and developed players such as Brett Gardner, Dellin Betances and vital rookies Greg Bird and Luis Severino.

Video: MLB.com looks at the makeup of the 2015 Astros

The biggest surprise in the playoffs had the most blended approach. The Astros have improved from 51 to 70 to 86 wins over the last three seasons thanks to a mixture of first-round picks (Carlos Correa, George Springer), Draft steals (seventh-rounder Dallas Keuchel), bargain international signings (Jose Altuve), trades for veterans before (Evan Gattis, Luis Valbuena) and during (Scott Kazmir, Carlos Gomez, Mike Fiers) the 2015 season, waiver claims (Collin McHugh, Will Harris) and free agents (Luke Gregerson, Colby Rasmus).

Which approach will work best in 2015? We'll know for sure in four weeks.