In the aftermath of the Mets' dismal 2009 season, some commentators in the Mets blogosphere argued that the team's woes stemmed from Omar Minaya's failure to surround his core group of players -- David Wright, Jose Reyes, and Carlos Beltran -- with "complementary" players.   This argument makes sense on a gut level, but it raises an important question: what do we mean when we talk about "complementary" players? To answer this question, I compared the Mets' roster over the last four seasons to the Phillies' roster over the same time period. I chose the Phillies as a comparable team because, like the Mets, the Phillies' roster has been built around a three-player offensive core -- Chase Utley, Ryan Howard, and Jimmy Rollins.  By isolating these core players and focusing on each team's Top 7 non-core offensive WAR producers, we can see what types of players outside the core helped to contribute to each teams' offensive production over the last four seasons.

2006 Rosters

The two offenses produced nearly identical WAR numbers from their Top 10 offensive contributors (31.1 WAR for the Phillies, 30.2 WAR for the Mets).  While the Phillies' core produced nearly two more wins than the Mets' core in 2006, the Mets' complementary players produced nearly a win more than the Phillies' complementary players.  What's interesting here is the variance in the distribution of each team's complementary player production.  The Mets produced a higher total complementary player WAR on the backs of its top-four complementary players -- Lo Duca, Valentin, Delgado, and Chavez -- who cumulatively produced 11.8 WAR.   The Phillies, on the other hand, received at least a win of production from each of its complementary players, but its top-four complementary players fell 3.1 wins short of matching the Mets' top-four complementary players.  Thus, the Mets relied on top-heavy production from its complementary players, while the Phillies received a more even distribution of production from its complementary players.  

2007 Rosters

The importance of complementary players comes into focus in 2007.  Each team's core produced around 19 wins, but the Phillies' complementary players nearly doubled the production of the Mets' complementary players.  Like the Mets in 2006, the Phillies' top-four complementary players produced the majority of the Phillies' complementary player WAR.  But the Phillies also received decent production from its bottom-three complementary players, with Ruiz, Iguchi, and Dobbs combining for 3.8 WAR.  Compare that to the Mets bottom-three complementary players in 2006, who produced only 1.3 WAR.  The Mets did receive more consistent production from its complementary players in 2007, as almost all of the complementary players produced at least 1 WAR.  However, the Mets' top-four complementary players produced 5.4 fewer WAR than their 2006 counterparts, thus resulting in overall lower WAR production for the Mets' complementary players in 2007 than in 2006.

2008 Rosters

The Mets' core had its best performance in 2008, but the complementary players once again finished with a lower WAR total than their 2006 counterparts.  Additionally, as in 2007, only one Met complementary player finished the season with more than 2 WAR, whereas 4 Met complementary players finished above 2 WAR in 2006.  The Phillies' complementary players outperformed their team's core, led by their top-three WAR producers who totaled 12.6 WAR.  

2009 Rosters

Each team's core produced its lowest WAR total of the four-year period, but the loss of production from the Mets' core was far more precipitous, totaling an astonishing 13 fewer wins than in 2008.  The Mets' complementary players also produced their lowest WAR total, but the group's 2009 total only fell short of its 2007 and 2008 performances by 1.0 WAR and 1.7 WAR respectively.  Once again, the Phillies' complementary players outperformed their team's core, with the top-three complementary players producing 12.3 WAR.  

Conclusion 

A comparison of the Mets' and Phillies' rosters shows that complementary players, defined as the Top 7 WAR contributors outside a team's superstar players, can make or break an offensive lineup.  That's not surprising, considering that this definition of complementary players includes more than half of a team's offensive players. However, if we look closer at the numbers above, I think we can pinpoint exactly what type of complementary players the Mets lack.

In the 2007-2009 seasons, the Phillies' complementary players destroyed the Mets' complementary players, outproducing them by 7 to 9 WAR in each season.  What was the biggest difference between each team's complementary players?  In each of those three seasons, the Mets failed to carry more than one complementary player who produced more than 2 WAR, and no single complementary player produced a WAR total above 3.  During the same time period, the Phillies produced 11 complementary players with more than 2 WAR (4 in 2007, 3 in 2008, and 4 in 2009) and 8 players with more than 3 WAR (2 in 2007, 3 in 2008, and 3 in 2009).  What the Mets were missing during these seasons were players who could produce between 3-5 WAR seasons to complement the 5-8 WAR seasons that the Mets could expect from Beltran, Wright, and Reyes (at least in 2007 and 2008). Thus, when we talk about the Mets' lack of "complementary" players, we mean that the Mets are lacking Jayson Werth, Shane Victorino, and Raul Ibanez -- players that can be an All-Star in any given season but who fall short of putting up superstar numbers on a consistent basis.  

Fortunately, the Mets' recent signing of Jason Bay gives the team exactly the type of complementary player it needs. CHONE projects Bay to contribute 4 WAR to the Mets in 2010, which should be a welcome addition to the team's group of complementary players if Wright, Beltran, and Reyes can return with 5+ WAR seasons.  In addition, if Pagan can somehow convince the Mets that he should start in RF over Francoeur, he has the potential to put up 3+ WAR in a full season of at-bats, as he's already produced 3.2 WAR as a Met in about 500 PAs.  However, none of the other Mets' complementary players, such Jeff Francoeur, Daniel Murphy, Luis Castillo, and (most likely) Bengie Molina, project to produce more than a 2 WAR season.  But if these four players can cumulatively produce somewhere around 8 WAR, and Bay and Pagan combine for 8 WAR, and the core produces 15+ WAR, the Mets' lineup will produce on the same level as in 2006-2008, when the Mets played meaningful games in September.  That might be wishful thinking, but it's a result that doesn't seem too far outside the realm of possibility.