3 high-upside depth free agents the Pittsburgh Pirates should add immediately

Depth is something every good major league team needs. You never know when a player is going to go down with an injury, or when other circumstances will force a player to miss time, sending a team down into the high minors to nab a solution. The Pittsburgh Pirates in 2025 had plenty of pitching depth, but decidedly lacked when it came to position players. The approach they should take this offseason to adding depth involves adding players with upside, and they could easily add all of these players, who will more than likely have to settle on minor league contracts this offseason.

The Pirates could also sign them right now, like the Red Sox just did with ex-Pirate Jason Delay, as all three have already elected free agency.

3 high-upside depth additions the Pirates could make right now

Alexis Diaz

If there's one thing you can credit the Pirates for, it's funding decent relievers from seemingly nowhere. However, Alexis Diaz would come with more previous success in the major leagues than recent Pirates additions Dennis Santana, Justin Lawrence, and especially Isaac Mattson. At one point, Diaz looked like he was on his way to becoming one of baseball's top closers. But now, he is likely looking at a minor league contract.

The first 1.5 seasons for Diaz's MLB career were great. Between 2022 and the first half of 2023, Diaz tossed 104.1 innings of work, working to the tune of a 1.90 ERA, 2.92 FIP, and 0.99 WHIP. He struck out just a shade over a third of batters, with a 34.4% K%, while holding opponents to an 0.52 HR/9, 87.7 MPH exit velocity, and 7.5% barrel percentage. His 12.4% walk rate was about the only blemish in his career up to that point. Diaz also registered a strong 106 Stuff+ grade during this time, 6% above-average.

However, cracks in the armor began to show during the second half of 2023, bleeding into 2024. Diaz's subsequent 83 frames saw him put up a 4.23 ERA, 4.83 FIP, and 1.34 WHIP. His K% dropped significantly to 21.8%, and his HR/9 also rose to 0.98. Diaz's already poor walk rate climbed even higher to 13.3%. But what was most worrisome was his massive dip in Stuff+ to just 91.

Things have completely spiraled out of control from there. Diaz opened the 2025 campaign on the IL, but allowed eight earned runs in his first six innings of work this past season. He was eventually optioned to the minor leagues, but soon traded to the LA Dodgers, where he logged just nine innings, allowing five more earned runs and two home runs. He struggled so much that the Dodgers DFA'd him in early September, and he was then claimed off waivers by the Braves. He closed out his 2025 season with Atlanta, allowing three more ER in 2.2 innings. 

Diaz has since elected free agency, making him available for anyone to sign him right now. The Pirates have helped plenty of relievers find their groove in the last few seasons, but Diaz would come to Pittsburgh with the most previous success. Signing Diaz on a minor league contract would come with zero risk, and the Pirates' recent history has proven they can figure out relievers in a similar situation to the right-hander's current dire straits.

Jose Siri

Jose Siri was acquired by the New York Mets last offseason with the hope he could provide some pop and a strong glove in center field. However, he missed most of the year with a broken tibia, appearing in just 16 games, recording two hits and 17 Ks in 36 plate appearances. He was then DFA'd during late September, and outrighted to Triple-A. However, when he is healthy, Siri is a potential Gold Glove center fielder with 20/20 power and speed.

During his time with the Tampa Bay Rays, Siri hit .210/.266/.414 with a .292 wOBA and 91 wRC+ over 990 plate appearances. Siri struck out over a third of the time with a 36.4% strikeout rate, and only drew a walk at a well-below-average 6.3% rate. Still, he provided good power, with 47 home runs and a .204 isolated slugging percentage. He led all Rays hitters who recorded at least 500 plate appearances between 2022 and 2024 in barrel rate (12.4%). Plus, Siri swiped 34 bases in 45 attempts.

Siri's offense wasn't great, but it was playable when paired with his defense. Siri had +14 defensive runs saved with a whopping +32 outs above average with the Rays. Since making his debut with the Houston Astros in 2021, his +39 OAA is the sixth-best total in baseball. He has plenty of range and was in the 98th and 99th percentile of sprint speed in 2023 and 2024, respectively. Siri has a cannon for an arm, as he's been above the 90th percentile of arm strength every year of his career.

Siri elected free agency, and since he was outrighted off the Mets' 40-man roster prior to the end of the year, he is eligible for minor league free agency. The Pirates do not have much depth in center field. When Oneil Cruz wasn't taking the field, it was either Jack Suwinski or Alexander Canario at the position. For an outfielder with the level of speed, defense, and power Siri can provide, you could do much worse for a Triple-A depth stash.

Cionel Perez

Diaz isn't the only reliever who was solid in 2022-2023, but struggled the last two years and is now looking at a minor league contract. Southpaw Cionel Perez broke out in a big way with the Baltimore Orioles during his first two years with the club, but 2024 was an abysmal season for the relief pitcher, and 2025 was even worse, leading to free agency.

Between 2022 and 2023, Perez owned a 2.43 ERA, 3.30 FIP, and 1.35 WHIP. Both his 20.6% strikeout rate and 10% walk rate were below average, but he made up for that by inducing a ton of ground balls and poor contact. His 56.2% ground ball rate was the 11th best among relievers in 2022-2023 with at least 100 innings pitched. His 4.6% barrel percentage was also the 15th best mark, while his minuscule HR/9 of 0.32 was the fourth best total.

The good news is that Perez has continued those particular trends in 2024 and 2025, while collapsing elsewhere. During that span, he's posted an 0.36 HR/9, a 56.5% grounder rate, and a 4.4% barrel rate. However, that's about where the positives end. Perez still has a poor 5.62 ERA, 4.01 FIP, and 1.61 WHIP over his last 75.1 innings pitched. His already poor walk rate has only gotten worse, coming in at 13.2%. He hasn't made up for it with more Ks, clocking in with a K% of 19.3%.

Perez also elected minor league free agency around the time of Siri. Again, the Pirates are not unfamiliar with taking relievers who have struggled in the major leagues and turning them into something useful. Perez still has a 104 Stuff+ over the last two years, so he can still give the Bucs something to work with - and a lefty arm at that.