A player's value in free agency often comes down, in large part, to timing.
On one end of the spectrum, J.D. Martinez crushed his way to a career season before hitting the market -- including a torrid run down the stretch for the postseason-bound D-backs. That's the type of performance that will attract plenty of suitors.
Of course, few manage to put themselves in such a favorable position. For some, a down year came at the worst possible time. MLB.com's Mike Petriello recently looked at two free agents -- outfielder Hyun Soo Kim and pitcher Anibal Sanchez -- whose Statcast™ metrics suggest better things may be ahead after a rough 2017.
• Hot Stove tracker
Here are three more available players, none of whom produced a positive Wins Above Replacement (WAR) figure last season, who offer intriguing upside for teams looking for alternatives to the more high-profile free agents.
Carlos Gonzalez, OF
2017 WAR: -0.2
Gonzalez enters the free-agent market with a strong track record that includes three All-Star selections, three Gold Glove Awards and two Silver Slugger Awards. But unfortunately for Gonzalez, that success didn't extend into 2017, when he posted an 84 weighted runs created plus (wRC+), well below the league average of 100 -- with 14 home runs in 136 games.
Yet, there are a few reasons to believe Gonzalez will bounce back in 2018 -- even at age 32 and leaving Coors Field. For one thing, he was a productive player in both of the previous two seasons, batting a combined .285/.337/.522 (113 wRC+) with 65 homers and a 5.4 WAR.

And while Gonzalez's numbers were down across the board in 2017, his final month showed that plenty of life remains in his bat. The sweet-swinging lefty posted a .377/.484/.766 line over his final 24 games going back to Sept. 1, with 12 doubles, six homers and 15 walks. Even more encouraging were his Statcast™ metrics. Among 217 hitters who put at least 50 balls in play from Sept. 1 on, only Aaron Judge and Martinez topped Gonzalez's 56.6-percent hard-contact rate (95-plus-mph exit velocity).
Gonzalez also told USA Today that a late-August visit to a sleep specialist helped spur that dramatic turnaround. Perhaps being consistently well-rested can carry his September success into 2018.
Chris Tillman, SP
2017 WAR: -2.2
There's no way to sugarcoat Tillman's 2017 results. Among pitchers with at least 90 innings, he had the highest ERA (7.84), Fielding Independent Pitching (6.93), WHIP (1.89) and OPS allowed (.981), and the lowest strikeout-to-walk ratio (1.24).
Yet, Tillman will only turn 30 on April 15, and from 2012-16, he was a stellar part of the Orioles' rotation -- in the American League East, no less -- making 143 starts. Tillman was one of just 53 pitchers to throw at least 750 innings over those five years, and his 108 ERA+ (100 is league average) was right in the middle of that pack at 26th. That type of performance has significant value.

As rough as Tillman's 2017 was, there were extenuating circumstances. He spent time on the disabled list with right shoulder bursitis late in '16, and the issue then forced him to miss Spring Training and all of April. It may also have affected his velocity, which was down almost 2 mph. Interested clubs have to consider the possibility that those shoulder issues will persist or have a lasting effect. But if Tillman goes into next season healthy, it's not difficult to envision a sizeable rebound -- especially if he moves to the National League and/or a friendlier environment than Camden Yards.
Doug Fister, SP
2017 WAR: 0.0
Coming off a replacement-level 2016 with the Astros, Fister didn't get back to the big leagues until late June, pitching 90 1/3 innings over 18 games (15 starts) for the Red Sox. And while his 4.88 ERA and 94 ERA+ don't stand out, they also don't tell the whole story for Fister, who turns 34 in February.
Fister's FIP, which focuses only on the factors a pitcher can control (strikeouts, walks and homers), was better than average at 3.98. The right-hander's .310 expected wOBA (xwOBA) allowed -- which considers quality of contact, plus strikeouts and walks -- was better than the .320 MLB average for starters in 2017. Among the notable pitchers who posted an xwOBA within a few points of Fister were Gerrit Cole, Michael Fulmer, Sonny Gray, Lance Lynn, Marcus Stroman, Masahiro Tanaka and Justin Verlander.

Over Fister's final 11 starts, from July 31 on, his .294 xwOBA allowed ranked 24th out of 90 pitchers with at least 200 batters faced -- just behind Dallas Keuchel. Combine that with an overall fastball velocity (89.7 mph) that jumped by more than 2 mph over 2016 -- and was 90.5 mph in September -- and Fister could be a good gamble for a club looking to fill out the back of its rotation.