What makes a good Mets free agent signing

The Mets’ re-signing of Yoenis Cespedes capped off one of the team’s busiest offseasons in recent memory. In addition to the Cespedes signing, the Mets traded for second baseman Neil Walker, signed free agent shortstop Asdrubal Cabrera, and made a few other moves to solidify their rotation and bullpen.

The Mets have had similarly exciting offseasons before, some yielding terrific seasons (2006) and others resulting in disappointing ones (2002). To get a sense of what makes a good acquisition—be it via trade or free agency—I looked at every prominent acquisition of major league-ready players the Mets have made in their history. In doing so, I tried to determine if there was any one factor that predicted whether the player met, outperformed, or underperformed expectations. It turns out that there is such a factor: the player’s age.

It’s no secret that a player’s age has a great impact on his physical abilities, and therefore his performance. But it’s striking just how big of an impact it has.

Below is every Mets acquisition, broken down by his age at the start of his first season with the team. If the player turned 29 in July of his first year as a Met, he is listed under his age 28 season. Listed next to each player are his average fWAR in his three seasons prior to joining the Mets, his average fWAR during the years he played for the Mets, and the change from the first average to the second. If the Mets acquired the player in the middle of the season, that season is listed as one with the Mets, not with his previous team.

There are a few things to keep in mind when looking at these breakdowns. First, the length of a player’s Mets tenure does not always match the three-year sample we use to establish their baseline expectations. Some players were a Met for only one year, while others were on the team for five or six. Therefore, as an example, we may be comparing a three-year pre-Mets average to a five-year average with the Mets. For those players, like Carlos Beltran, who played for the Mets for many years, their relatively lower WAR totals later in their Mets careers may drag down their overall Mets averages. The lessons there may concern the length of the investment, rather than the wisdom of investing in the first place.

Second, all of the usual disclaimers about small sample sizes apply. It’s never a good idea to draw definitive conclusions based on a sample of 73 players. Still, the experiences of 73 players, who all came to the Mets in similar circumstances, offer a very revealing look into the nature of trade and free agent acquisitions.

Age 24 season

Player	Average fWAR in three seasons before joining Mets	Average fWAR with Mets	Change in average fWAR
David Cone*	0.1**	4.3	+4.2
Howard Johnson	0.7	2.5	+1.8
Average	0.4	3.4	+3.0

*First stint with Mets. **One season in MLB.

Age 25 season

Player	Average fWAR in three seasons before joining Mets	Average fWAR with Mets	Change in average fWAR
Tommie Agee	3.5	3.0	-0.5
Average	3.5	3.0	-0.5

Age 26 season

Player	Average fWAR in three seasons before joining Mets	Average fWAR with Mets	Change in average fWAR
Armando Benitez	0.8	1.4	+0.6
Dave Kingman*	1.8	1.5	-0.3
Average	1.3	1.5	+0.2

*First stint with Mets.

This group seems to be the first appropriate cutoff. The age 24-26 players are the only ones who, as a whole, improved when they got to the Mets. The players in every subsequent group saw at least some decline after arriving in New York. More on that soon.

Age 27 season

Player	Average fWAR in three seasons before joining Mets	Average fWAR with Mets	Change in average fWAR
Carlos Baerga	2.9	-0.3	-3.2
Carlos Beltran	6.2	4.3	-1.9
Roger Cedeno*	0.6	-0.4	-1.0
Mike Hampton	3.4	4.6	+1.2
Kevin McReynolds	3.6	2.9	-0.7
Francisco Rodriguez	1.9	1.1	-0.8
Bret Saberhagen	4.9	3.1	-1.8
Average	3.4	2.2	-1.2

*Second stint with Mets.

Age 28 season

Player	Average fWAR in three seasons before joining Mets	Average fWAR with Mets	Change in average fWAR
Tommy Davis	1.1	2.7	+1.6
Bobby Ojeda	2.6	2.3	-0.3
John Olerud	2.6	6.1	+3.5
Juan Samuel	2.2	0.2	-2.0
Rusty Staub*	5.9	1.8	-4.1
Frank Viola	4.9	4.4	-0.5
Average	3.2	2.9	-0.3

*First stint with Mets.

Age 29 season

Player	Average fWAR in three seasons before joining Mets	Average fWAR with Mets	Change in average fWAR
Bobby Bonilla*	4.3	2.8	-1.5
Yoenis Cespedes	2.9	6.7**	+3.8
Vince Coleman	2.0	0.6	-1.4
John Franco	1.3	0.7	-0.6
Bernard Gilkey	2.4	3.2	+0.8
Keith Hernandez	5.2	3.9	-1.3
Braden Looper	0.6	0.6	0.0
Brian McRae	2.6	0.9	-1.7
Mike Piazza	7.2	3.5	-3.7
Johan Santana	5.9	4.0***	-1.9
Average	3.5	2.7	-0.8

*First stint with Mets. **2016-2018 TBD. ***DNP 2011 or 2013.

Players in the age 27-29 group were, overall, productive when they got to the Mets. While they didn’t suffer a huge drop-off, there was a bit of a decline—generally around 10-35%—from their previous levels of production. This is particularly interesting. It shows that if you want a player for his best years, you need to acquire him before he turns 27. If you acquire a player during his age 27 to 29 seasons, his best days are probably already behind him.

Bill James long ago refuted the conventional wisdom that a player’s peak typically ranges from his age 28 to 32 seasons. James suggested that the peak was actually closer to the 26-30 range. However, the experiences of the players listed here suggest that the peak range might be even younger. A few recent studies that we’ll discuss later confirm that that’s likely the case.

Age 30 season

Player	Average fWAR in three seasons before joining Mets	Average fWAR with Mets	Change in average fWAR
Cliff Floyd	4.2	1.8	-2.4
Jim Fregosi	4.1	-0.1	-4.2
Willie Montanez	1.1	0.4	-0.7
Chris Young*	2.6	0.4	-2.2
Average	3.0	0.6	-2.4

*Outfielder.

Age 31 season

Player	Average fWAR in three seasons before joining Mets	Average fWAR with Mets	Change in average fWAR
Jason Bay	2.2	0.3*	-1.9
Mike Cameron	5.4	3.0	-2.4
Gary Carter	7.4	2.6	-4.8
Luis Castillo	3.1	1.3**	-1.8
Randy Jones	3.0	-0.6	-3.6
Ray Knight	2.4	0.4	-2.0
Shaun Marcum	2.9	1.4	-1.5
Robin Ventura	4.2	4.0	-0.2
Average	3.9	1.6	-2.3

*DNP with Mets 2013. **DNP 2011

Age 32 season

Player	Average fWAR in three seasons before joining Mets	Average fWAR with Mets	Change in average fWAR
Pedro Astacio	3.6	0.3	-3.3
Jeromy Burnitz*	2.8	1.0	-1.8
Lance Johnson	3.0	4.2	+1.2
Dave Kingman	2.4	0.0	-2.4
Al Leiter	2.6	3.4	+0.8
Average	2.9	1.8	-1.1

*Second stint with Mets.

Age 33 season

Player	Average fWAR in three seasons before joining Mets	Average fWAR with Mets	Change in average fWAR
Kevin Appier	1.6	3.4	+1.8
Donn Clendenon	2.7	1.3	-1.4
Carlos Delgado	3.7	1.5	-2.2
George Foster	4.4	1.0	-3.4
Curtis Granderson	3.7	3.2*	-0.5
Shawn Green	1.7	-0.3	-2.0
Paul Lo Duca	2.1	1.3	-0.8
Pedro Martinez	6.5	2.5	-4.0
Average	3.3	1.7	-1.6

*2016-2017 TBD.

Age 34 season

Player	Average fWAR in three seasons before joining Mets	Average fWAR with Mets	Change in average fWAR
Roberto Alomar	6.3	0.9	-5.4
Ken Boyer	4.0	1.9	-2.1
Hubie Brooks*	1.4	0.4	-1.0
Joe Torre	3.1	0.7	-2.4
Mo Vaughn	3.4**	-0.2	-3.6
Billy Wagner	2.0	1.3	-0.7
Todd Zeile***	2.4	1.8	-0.6
Average	3.3	1.0	-2.3

*Second stint with Mets. **DNP 2001. ***First stint with Mets.

Age 35 season

Player	Average fWAR in three seasons before joining Mets	Average fWAR with Mets	Change in average fWAR
Mickey Lolich	4.8	3.0	-1.8
Average	4.8	3.0	-1.8

Age 36 season

Player	Average fWAR in three seasons before joining Mets	Average fWAR with Mets	Change in average fWAR
Bobby Bonilla*	1.0	-1.3	-2.3
Michael Cuddyer	1.4	0.0	-1.4
Eddie Murray	3.6	2.0	-1.6
Duke Snider	1.6	0.7	-0.9
Average	2.0	0.4	-1.6

*Second stint with Mets.

Everything changes when players turn 30. As you can see, not only is there a drop-off, but a big drop-off in production at the age 30 season, and in each of the six seasons after that. From age 30 to 36, a player can expect at least a 50% decline in production from its level during his three previous seasons.

Age 37 season

Player	Average fWAR in three seasons before joining Mets	Average fWAR with Mets	Change in average fWAR
Tom Glavine	3.1	2.4	-0.7
Orlando Hernandez	2.0	2.1*	+0.1
Average	2.6	2.3	-0.3

*DNP 2008.

Age 38 season

Player	Average fWAR in three seasons before joining Mets	Average fWAR with Mets	Change in average fWAR
Tom Seaver*	0.8	2.4	+1.6
Average	0.8	2.4	+1.6

*Second stint with Mets.

Age 40 season

Player	Average fWAR in three seasons before joining Mets	Average fWAR with Mets	Change in average fWAR
Moises Alou	3.5	1.1	-2.4
Bartolo Colon	3.0	2.7*	-0.3
Rickey Henderson	2.0	1.3	-0.7
Orel Hershiser	2.2	1.9	-0.3
Willie Mays	4.5	1.1	-3.4
Average	3.0	1.6	-1.4

*2016 TBD.

Interestingly, the slide in production isn’t nearly as pronounced after players turn 37. For players in this group, particularly the pitchers, the drop-off is generally less than 50%. The most likely reason is that players who reach that age defy the traditional aging curve. Therefore, if a player hasn’t fallen off the production cliff by age 37, he probably won’t experience a sudden downfall after that.

Tom Glavine, Orlando Hernandez, and Bartolo Colon are good examples of durable players who declined very slowly in their later years. When the Mets acquired them, they clearly weren’t the players they were in their 20s, but they also weren’t significantly different than the players they were in their early 30s.

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While we’re only dealing with a sample of 73 players, the results are remarkably consistent with those of Fangraphs’ Jeff Zimmerman, who wrote a couple of articles about aging curves. His first article uses value runs to create an aging curve for the game’s best hitters since 1955. His second article examines a broader pool of hitters who played from 1982 to 2013, and bases its aging curve on their wRC+.

Both aging curves show similar results: Players generally peak from 24 to 26. Starting at 27, they experience a steady decline until 30. Once they hit 30, their production starts to drop precipitously.

To use other Mets players as examples, take David Wright and Jose Reyes. Wright’s peak lasted from 2005 to 2008, his age 22-25 seasons, when he averaged 6.5 fWAR a year. From age 26 to 30, his production dropped to 4.4 fWAR a year. From 2014 to 2015, his age 31 and 32 seasons, a host of injuries limited him to just 1.4 fWAR per year, on average.

Similarly, Reyes enjoyed his peak from 2006 to 2008, his age 22-24 seasons, when he averaged 5.7 fWAR per year. His production dropped to 3.1 fWAR per year from age 25 to 30. In 2015, his age 31 season, Reyes had his worst full year in the big leagues and was just a 0.5-fWAR player.

Getting back to what makes a good trade or free agent target, it appears that age is an extremely important factor to consider. Perhaps the problem with some of the Mets’ infamous busts, like Roberto Alomar and Jason Bay, wasn’t that they "couldn’t handle the pressure of playing in New York." Instead, maybe those players did what countless others did at their age: They stopped producing because their age caught up to them.

Granted, Alomar’s decline was the most dramatic of any player on the list. Still, he was already 34 years old when he made his Mets debut. Bay’s decline was actually less precipitous than other Mets players—including Gary Carter and Ray Knight—who the Mets acquired at exactly the same age.

Carter was excellent in 1985, his debut season with the Mets. But by 1986, he was already about half the player, by WAR, that he was in his final three seasons in Montreal. By 1987 and beyond, he was a shadow of his former self, and not even a 2.0-fWAR player.

Of course, that’s not to say that trading for Gary Carter was a mistake. The same goes for Mike Piazza, despite the fact that his most productive years were behind him when he joined the Mets in 1998. Both Carter and Piazza were extremely important players on signature Mets teams (and Piazza was still quite good in New York for a number of years). The point is that, when a team acquires a catcher who is 29-31 years old, that team shouldn’t expect him to be the player he was at 25-27.

Recent Mets signings prove a similar point. For example, last year was Michael Cuddyer’s age 36 season. When you sign a 36-year-old player, the risk of a dramatic decline comes with the territory.

Curtis Granderson signed with the Mets prior to his age 33 season. His last monster year in the big leagues came with the Yankees in 2011, at the age of 30, when he was a 6.8-fWAR player. From 2012 to 2014, his age 31 to 33 seasons, Granderson averaged just 1.8 fWAR a year. While he rebounded with an exceptional 5.1-fWAR season in 2015, it’s fair to expect that, given his age, he will be closer to a two-win player during his final two years as a Met than the five-win player he was last year. Indeed, ZiPS projects Granderson for 2.6 WAR in 2016.

In this year’s free agent class, several players raise red flags. Former Mets target Ben Zobrist is one. Zobrist is entering his age 34 season and is coming off of his worst full season in the majors, by WAR. It’s true that Zobrist was at least a five-win player in three of the last four years. However, given his age, no one should expect him to repeat that in his next four years in Chicago.

Yoenis Cespedes is a bit of a different story. Although the outfielder is entering his age 30 season, 2016 will be only his fifth year in American baseball. By WAR, Cespedes just enjoyed his best season and has actually improved in each of his last three. For those reasons, it’s fair to not expect a precipitous drop-off in 2016. At the same time, his age does make it a risky proposition to bet on him long-term, which the Mets adamantly refused to do.

Like Cespedes, Neil Walker and Asdrubal Cabrera are entering their age 30 seasons. And, like Cespedes, it seems silly to suggest that acquiring them—or Granderson, for that matter—was a terrible mistake. Each of those players has been at least somewhat productive in recent years, and could help the Mets contend for the playoffs or World Series. It’s just worth understanding, based on the track records of countless players, the risks involved in acquiring players on the wrong side of 30.

On the bright side, the Mets have several young players entering what should be the primes of their careers. Michael Conforto will be 23 by Opening Day, and Wilmer Flores is 24. Among the team’s vaunted starting pitchers are Noah Syndergaard (age 23), Steven Matz (age 24), and Zack Wheeler (age 25). These talented young players should complement the established veterans the team acquired from outside the organization to make the Mets a strong, balanced team heading into 2016.