There isn't an MLB team in the league that doesn't think that they are improving the club when they make a deal at the trade deadline as buyers. These teams are trying to mortgage some future assets to get immediate returns in the name of a push into the postseason. However, those trades don't always work out as planned. And in many of those cases, the signs were there leading up to the trade deadline that the players on the move should've had a buyer beware sticker.
To some degree, what players, both hitters and pitchers, have done in a given season leading up to the trade deadline does matter. At the same time, with all of the data and underlying metrics that both fans and teams now have at their disposal, we can also look at players who actually be buy-high type of additions who are destined or at least likely to regress.
In that light, let's dive into six players who are rumored to be on the trade block leading up to the deadline, why they should be buyer beware based on the numbers, and which potential trade fits should be cautious about acquiring any of these players.
6. SP Tyler Mahle (Texas Rangers)
It's not a guarantee that the Texas Rangers will be sellers at the trade deadline. In fact, their investment in the roster suggests that they might not be. However, that doesn't mean that they still couldn't look to cash in on Tyler Mahle in the midst of a phenomenal season for the veteran right-hander. Through 14 starts this season, Mahle has posted a pristine 2.34 ERA with a 1.13 WHIP. For teams in need of rotation help, he certainly looks attractive.
When you dig into the underlying numbers, however, there are viable questions. For one, his expected ERA is nearly two full points higher (4.14) than his mark for the season while his velocity is lacking in comparison to league average as well. Perhaps most notably, his strikeout rate is only in the 25th percentile this season while also having a middling 8.8% walk rate. When you combine that all together, it does create an indication that serious regression could be coming sooner than later.
Buyers that should beware: Chicago Cubs, Los Angeles Dodgers, Minnesota Twins
5. IF Isiah Kiner-Falefa (Pittsburgh Pirates)
USA Today MLB insider Bob Nightengale reported that the Pirates are already receiving calls on veteran utility infielder Isiah Kiner-Falefa. For a team that's been largely starved for consistent offense, it's not hard to see why teams have inquired about IKF on the surface. Though the power will never really be a factor, Kiner-Falefa has been more than solid with a .298/.315/.353 slash line on the year.
That, however, might be a bit of smoke and mirrors. Kiner-Falefa's expected batting average is just .277 while his expected wOBA is only .301 on the year. Essentially, the underlying numbers suggest that IKF has gotten quite lucky at the plate so far this season. When you then consider that he's only fourth perecentile in average exit velocity, barrel rate and hard hit rate, that makes even more sense. As such, teams should be wary of adding a bat primed for regression with no pop.
Buyers that should beware: Kansas City Royals, San Francisco Giants, Los Angeles Dodgers
4. RP Kyle Finnegan (Washington Nationals)
Admittedly, Kyle Finnegan isn't as much of a buyer beware as some of the other guys on this list. His underlying numbers certainly suggest that he's been quite lucky to enjoy the season he has. While he's posted a stellar 2.25 ERA, the first sign that might be a bit misleading is a 1.25 WHIP that doesn't totally match up. However, it's even more enlightening to see that he has an expected ERA at 3.68 this season, a full 1.43 points higher than the mark he's posted.
What stands out further is that the expected numbers for Finnegan are actually in line with the player he's simply been throughout his career. From 2021 through last year in 2024, his ERA was between 3.55 and 3.76. All that is to say, Finnegan has been a solid reliever and could be a nice addition to a lot of bullpens. However, the word of caution would be for teams not to expect the 2.25 ERA the Nationals have seen this season to continue for the remainder of the 2025 season.
Buyers that should beware: Philadelphia Phillies, New York Mets, New York Yankees
3. SP Andrew Heaney (Pittsburgh Pirates)
While Paul Skenes rightfully dominates the majority of the headlines with the Pittsburgh Pirates rotation, the truth of the matter is that Andrew Heaney has been crushing it all the same in that group as well. Through 13 starts this year, the veteran southpaw has produced steady as a rock for the Buccos with a 3.24 ERA and 1.15 WHIP on the year. For a player with an ERA under 4.15 just once in a season since 2015,
And the Pirates should probably act quickly to sell on Heaney if they're going to as well because, well, he seems almost destined to revert to the form we've seen throughout essentially the past decade. Heaney's expected ERA is a brutal 4.70 so far this season, which is only made worse by the fact that he's not missing bats, falling in just the 21st percentile in terms of whiff rate this season. He could still be valuable rotation depth, but it's highly unlikely that he performs like the No. 2 he's been this year for Pittsburgh.
Buyers that should beware: Chicago Cubs, San Francisco Giants, Atlanta Braves
2. CF Cedric Mullins (Baltimore Orioles)
By all accounts, the Baltimore Orioles are going to end up as surprise sellers at the trade deadline as they've bottomed out. One of the most coveted names of an Orioles' sell on the trade market would surely be veteran outfielder Cedric Mullins. Despite the woes of Baltimore as a whole, Mullins has stood out, leading the team in home runs (10) and RBI (32) this season with a .233/.321/.376 slash line. What that doesn't tell you, however, is that he's been one of the luckiest hitters in baseball.
While his weighted OBA is .338 this season, his expected wOBA is at .307 for the year. He's been quite fortunate to get on base at the rate that he has, in addition to slugging as well as he has this season as well. Throw in the fact that, while he's still a good defender, that his defense has slipped in recent years, and Mullins looks the part of a player who might look better on the surface and on paper than the impact he would actually have on a contender.
Buyers that should beware: Philadelphia Phillies, Seattle Mariners, New York Mets
1. SP Erick Fedde (St. Louis Cardinals)
After the St. Louis Cardinals traded for Erick Fedde ahead of last year's deadline, he now figures to be one of the players that the Redbirds move this summer. While the Cards aren't going to be full-blown sellers, his expiring contract could ultimately make him one of a few players who allows John Mozeliak and the St. Louis front office to play the middle ground. However, they might want to try and get Fedde off the books before the extremely obvious regression comes for him.
Fedde has continued to be solid with his overall numbers, posting a 3.54 ERA (second best in the Cardinals rotation) with a 1.30 WHIP. What jumps off the page with Baseball Savant, however, is that he's sitting with an expected ERA at 5.28 this season, 1.74 points higher than the actual mark. With the contact he's giving up and the situations he's found himself in, he's simply not been as good as his current ERA would suggest. His stuff likely isn't going to tick up meaningfully to change that, which means any team pursuing him should expect him to not be as strongly impactful as he has been.
Buyers that should beware: Boston Red Sox, Cleveland Guardians, Los Angeles Dodgers