When it comes to walk-year performances, for every Prince Fielder and Jose Reyes who put up monster seasons just before hitting the open market, there is an Albert Pujols whose performance declines due to injuries, inconsistency or both. Though studies have shown that, in aggregate, players do perform better in their walk years, the difference is not overwhelming, averaging out to roughly an additional half-win above replacement according to Dayn Perry's figures in the 2006 book
The following lists were produced using the same statistic Perry used in his 2006 study, Baseball Prospectus's Wins Against Replacement Player (WARP), which combines offensive and defensive contributions. The rankings were determined by the difference in WARP between the player's walk-year performance and his performance in the season prior to his walk year.
The erratic Huff's 2010 spike had a lot to do with just how awful his 2009 season, also a walk-year, was. Huff hit just .241/.310/.384 for the Orioles and Tigers in '09, torpedoing his market value by hitting .189/.265/.302 for Detroit after being acquired in a mid-August waiver trade. As a first-baseman and designated hitter, that put him 1.2 wins below replacement on the season. He then signed a one-year, $3 million deal with the Giants and had the best season of his career, playing strong defense at first as well in both outfield corners, and helping to lead San Francisco to its first World Series title. The Giants rewarded Huff, who turned 34 in December, with the richest contract of his career: $22 million over two years. So far, his 2011 has thus far looked a lot more like 2009 than 2010; he's batting .246/.299/.396 with eight home runs.
When most baseball fans think of walk-year spikes, they think of Adrian Beltre's 2004 season. That year, the 25-year-old Beltre led the majors in home runs, more than doubling his previous best, while also setting career highs in runs (104), hits (200), doubles (32), RBIs, total bases (126 more than his previous career best), and all three slash stats. Beltre's season wasn't just big in comparison to his weak 2003, it was 5.2 WARP above his previous best season (2000), and it earned him a five-year, $64 million contract from the Marines. However, Beltre didn't come anywhere near approaching his '04 level of production until six years later, after he had finally escaped Safeco Park for Fenway Park and posted another 5.2 WARP spike in his 2010 walk year, large enough to rank sixth on this list (in part because his 2009 walk year with the Mariners was plagued by injury and poor performance).
The slugging catcher of the late-'90s Braves failed to impress in his first walk year in 2001 and settled for a one-year deal with an option for 2003. The Braves picked up that option, and Lopez, given a second chance, had the best season of his career at age 32, setting career highs in the same categories Beltre would a year later: runs, hits, doubles, home runs, RBIs, total bases, and all three slash stats. The result remains the fifth-best season by a catcher in the 21st century (third best in the non-Joe Mauer category) according to WARP. Unfortunately for Lopez, being a 33-year-old catcher limited his ability to cash in on that season on the open market, though he did land a three-year, $22.5 million deal from the Orioles and rewarded them with a very strong 2004 season before showing his age thereafter.
Boone arrived in Seattle in 2001 on a one-year deal as a 32-year-old journeyman, a slick-fielding second baseman with a bit of pop, but a poor plate approach, a career .255/.312/.413 hitter joining his fourth team in as many years. He then led the league in RBIs, won the Silver Slugger, and finished third in the MVP voting for Mariners team that, despite having just lost Alex Rodriguez to the biggest contract in baseball history, won a record-tying 116 games. Boone set career highs in games, plate appearances, at-bats, runs (118), hits (206), doubles (37), home runs, RBIs, total bases, and all three slash stats and was rewarded with a four-year, $33 million deal, during which he had one more outstanding season, and after which he promptly fell below replacement level and vanished from the league.
Figgins' 2009 season may not have seemed so out of line with his previous performances because he hit .330/.393/.432 just two years prior and was a career .290/.356/.387 hitter coming into the 2009 season, but he had never before combined such production with health and Gold Glove quality play in the field. Figgins appeared in just 114 games in 2007, but played 158 games in 2009 while setting career highs in plate appearances, runs scored, doubles, walks (a league-leading 101, none of them intentional), and on-base percentage. Those last two, which were a large part of his value in 2009, were the result of a steady increase in his walk rate over the course of his career, which promptly began to regress after he signed a four-year, $36 million contract with the Mariners.
Note: I've weeded out walk-year dips that corresponded to expected age-related declines. For example, while Derek Jeter's 3.1 dip in WARP in his 2010 walk-year was significant, it wasn't at all unexpected for a 36-year-old shortstop, and thus his season, and others like it, were not considered for this list.
Hidalgo was inconsistent and often injured, but as the Astros' centerfielder in 2000 he ranked 10th in the majors in WARP, prompting Baseball Prospectus to call him "dollar-for-dollar one of the 10 most valuable commodities in baseball." He earned a few down-ballot MVP votes after a strong 2003 season (.309/.396/.572), but his walk year in '04 was pure disaster. Traded to the Mets in June for a non-prospect minor league pitcher and veteran reliever David Weathers, Hidalgo hit .228/.296/.463 for the Mets while playing a sub-par right field. Still, the Rangers gave him $5 million for a one-year, make-good deal, and there remained hope that he would find himself in Arlington's hitting-friendly ballpark. Instead, he sunk below replacement level and disappeared from the game at the age of 30.
The well-traveled Sanders played for eight teams in nine years to start his thirties, regularly contributing something on the level of three wins above replacement as a complimentary outfield part, a power and speed threat who wasn't quite productive enough to be a star but nonetheless finished his career as one of just six players in baseball history with 300 career home runs and 300 career steals (since joined by a seventh man, Alex Rodriguez). Sanders changed teams as a free agent five times, the first time following his worst major league season, and only one with the Braves, in 2000. That injury-riddled campaign came on the heals of one of his best seasons, a .285/.376/.527 performance with 26 home runs and 36 steals for the Padres in 1999. Sanders wouldn't receive a multi-year contract until 2004.
Damon's time with the Red Sox and Yankees was so successful that it's easy to forget how miserable his preceding lone season with the A's was. Damon was one of the rising stars in the game when he was acquired from the Royals in a classic Billy Beane trade that involved three teams (also the Devil Rays), and seven players (including Mark Ellis, who is still with Oakland). He led the American League in runs and stolen bases in 2000, receiving some down-ballot MVP votes for his efforts, had improved in every season of his career, and was going to be just 28 in the first year of his free agency. Beane acquired him to get the compensation draft pick the next year (which worked and netted the A's Nick Swisher), but the Oakland Coliseum was the wrong place for Damon to spend his walk year. He hit just .247/.333/.323 at home in 2001, and only marginally better on the road. Still, the Red Sox gave him a four-year, $31 million deal, and Damon rebounded nicely in hitter-friendly Fenway Park.
Prior to his final season in Atlanta, Jones looked like he was headed to the Hall of Fame. He had hit 342 home runs prior to his 30th birthday, won nine straight Gold Gloves, and was an iconic player on one of the great dynastic teams in the game's history. In 2005 he had his best season yet, leading the majors with 51 home runs, and followed up with 41 dingers and a career-best 129 RBIs in 2006. Then came 2007. It looked like a fluke at the time; Jones had always been something of an inconsistent and undisciplined hitter. Still, it caused trepidation on the market. The Dodgers gave him dollars ($36.2 million) but not years (two), and quickly regretted even that. An out-of-shape and often-injured Jones hit just .158 for L.A. in 2008, and has since had to scratch out a career as a fourth-outfielder. By hitting just .212/.311/.411 over the last four-plus seasons, he has effectively driven his Hall of Fame campaign bus into a ditch several exits shy of Cooperstown.
In retrospect, it's all the more impressive that the Red Sox won their first World Championship in 86 years in 2004 given that Martinez and Derek Lowe, two fifths of their starting rotation, shed nearly four wins of value from the year before. Martinez was coming of perhaps the greatest run of pitching dominance in the game's history. For seven years, from 1997 to 2003, most extreme run-scoring era in the game's history, he posted a 2.20 ERA, good for a 213 ERA+, struck out 11.3 men per nine innings with a 0.94 WHIP and a 5.59 K/BB, and won three Cy Young Awards. In 2003, he led the majors in ERA (2.22) and the AL in strikeout rate (9.9 K/9). In 2004, however, he looked human. He wasn't bad by any standard other than his own. Even his 4.24 ERA in the second half was better than league average, and one could argue that my edict against age-related declines should rule him out here, but he was still just 32 in 2004 and still held such sway over the game that the Mets gave him $53 million for the next four years. For their money, the Mets got one excellent season and three filled with frustration, disappointment, and injury.