Every season, there are a handful of impending free agents who run into untimely injuries, leading to a lack of production and, in turn, reduced interest when they hit the open market.

Sometimes, such players are still able to do well in free agency, even if they need to settle for a one-year "pillow contract" to rebuild their value. After struggling in his return from Tommy John surgery last season, Didi Gregorius was able to land a one-year, $14 million with the Phillies. Similarly, Josh Donaldson got $23 million from the Braves on a one-year pact last offseason after dealing with a left calf issue in 2018.

Not everyone is so fortunate, however. The seven players below remain unsigned after battling injuries in 2019. But don't write them off just yet. With better health this season, each could prove to be a crucial component for his next team.

Alex Wood, LHP

Among the 60 pitchers who threw at least 800 big league innings from 2013-18, Wood's 3.29 ERA ranked 12th, and his 3.36 FIP was 13th. Then came 2019, when Wood didn't make his first appearance until July 28 due to a back injury. The left-hander then posted a 5.80 ERA and a 6.38 FIP over seven starts before being shut down again with the same ailment. Back issues can be difficult to shake, but Wood is entering his age-29 season, and he doesn't have a ton of innings on his arm (839 in regular season), making him a great buy-low target.

Steven Souza Jr., OF

After playing only 72 games in 2018 due to a recurring right pectoral strain, Souza missed all of last season following surgery to repair a torn ACL, LCL, PCL and posterolateral capsule in his left knee. Moreover, Souza has logged more than 120 games played only once in his career, and he will turn 31 years old in April. The odds are against him making a sizable impact in 2020. Still, Souza was running at 100 percent intensity in December, and he could provide plus power and a capable glove for a fraction of what it will cost to sign fellow corner outfielders Nicholas Castellanos, Marcell Ozuna or Yasiel Puig.

Taijuan Walker, RHP

You might have missed Walker's brief return from Tommy John surgery, as it came on the final day of the 2019 regular season -- roughly 17 months after he underwent the elbow procedure -- and included just 15 pitches in a scoreless inning of work. Like Souza, Walker was non-tendered by the D-backs in November, making him a free agent. Still just 27 years old, Walker will enter the 2020 campaign with a lifetime 3.95 ERA, a 1.25 WHIP, an 8.1 K/9 and a 2.8 BB/9. With the benefit of a fully healthy offseason, the right-hander has the potential to be a viable back-end starter for a pitching-needy team.

Scooter Gennett, 2B

Gennett's 2019 season was derailed before it even began, as the veteran second baseman suffered a right groin strain late in Spring Training. He struggled upon returning to the Reds' lineup, and a July trade to the Giants did nothing to spark his bat. Overall, he hit .226/.245/.323 with two home runs, two walks and 41 strikeouts in 139 plate appearances. Gennett, though, was an All-Star as recently as 2018, and he produced 50 home runs with a .303/.351/.508 slash line over '17-18. While there are more than a few accomplished second basemen left on the market, Gennett arguably has more upside than any of them.

Jeremy Jeffress, RHP

Like Wood and Gennett, Jeffress began 2019 on the injured list due to a Spring Training ailment -- a right shoulder issue in Jeffress' case -- and was unable to get back on track once he returned. Before being released by the Brewers in September, he recorded a 5.02 ERA in 48 appearances. But even at age 32, the right-hander is a solid rebound candidate. Why? He was one of the most effective relievers in baseball two seasons ago (1.29 ERA), and he had a 160 ERA+ for the Blue Jays, Rangers and Brewers from 2013-18.

Collin McHugh, RHP

After an outstanding turn out of the Astros' bullpen in 2018 (1.99 ERA, 11.7 K/9), McHugh opened last season in Houston's rotation and pitched well early. However, he was moved back to the 'pen after a rough four-start stretch from April 21 to May 7 in which he gave up 24 earned runs in 18 innings, and he made only two relief appearances before spending more than a month on the IL with right elbow discomfort. McHugh was shelved again on Aug. 31 with a recurrence of the elbow problem, but he had a 2.70 ERA with a 10.2 K/9 over 25 appearances between IL stints. If his arm holds up in 2020, the 32-year-old could be a valuable swingman.

Domingo Santana, OF

Santana's past three seasons have been a roller-coaster ride. He was at his best in 2017, producing 30 home runs and an .875 OPS over 607 plate appearances for the Brewers, but he took a step back after being moved to a part-time role in '18, recording only five home runs with a .740 OPS in 235 PAs. Traded to the Mariners last offseason, Santana finished 2019 with an unremarkable 21 homers and a .770 OPS over 507 PAs. However, his production was considerably depressed by a rocky second half (three homers, .468 OPS), during which he dealt with right elbow soreness and tallied just 108 PAs. Prior to the All-Star break, Santana slugged 18 homers and had an .850 OPS. Although the 27-year-old is a poor defensive outfielder and a strikeout-prone hitter, he clearly offers a potent bat when everything is clicking.