Fantasy Baseball Trade Targets - Buy/Sell for Week 8 (2025)

Fantasy baseball trade candidates to buy/sell for Week 8 (2025). Joey's fantasy baseball undervalued players to target in trades, and overvalued to trade away.

We are several weeks into the new fantasy season, and trades should start picking up in your leagues. At this point in the year, fantasy managers begin to realize which players might be breaking out and which players might have been bad selections. It's also important not to completely overreact to slow starts from some star players. 

In this article, we will look at five players fantasy managers should buy or sell heading into Week 8 (May 19 to May 25) of the fantasy baseball season. The buy-low options are players who have gotten off to a slow start in 2025 and haven't been strong fantasy options in recent weeks. The sell-high options are players who are currently tearing it up but will eventually regress. 

So, which players should we buy and sell for Week 8 of the 2025 fantasy baseball season? Let's dive in and find out which players make the list. 

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Undervalued Fantasy Baseball Players to Trade For

William Contreras, C, Milwaukee Brewers

It hasn't been the perfect start to the season for Milwaukee Brewers catcher William Contreras. He is batting just .238 with four home runs, three doubles, and 21 RBI through his first 41 games in 2025. This slow start is a big difference from last year, considering Contreras was slashing .359/.434/.553 with six home runs, 13 doubles, and 34 RBI across his first 43 games. 

However, this rough stretch makes Contreras one of the best buy-low options heading into Week 8. Things will eventually pick up for the All-Star catcher, and his 3-for-4 performance against the Guardians on Wednesday could be a sign of him finally breaking out of his month-long slump. 

William Contreras unleashes a perfect throw to nab Pete Crow-Armstrong at second base! pic.twitter.com/FHArMDTKZP

— MLB (@MLB) May 4, 2025

It is also an encouraging sign that Contreras currently ranks in the upper half of the league in squared-up rate (27.6%), chase rate (24.5%), strikeout rate (18.5%), and walk rate (14.5%). Therefore, fantasy managers should expect better all-around numbers for the Brewers' catcher moving forward.

Let's not forget how consistent of a fantasy option Contreras has been in recent years. He has hit at least 20 home runs in two of the past three seasons and has brought in over 75 runs in back-to-back years. So, he's an easy buy in fantasy right now. 

Yordan Alvarez, OF/DH, Houston Astros 

There might be a slight buy-low window for Houston Astros outfielder Yordan Alvarez. He hasn't necessarily put up strong numbers to start the season and is currently on the 10-day injured list due to a hand injury. That makes now the perfect time to buy him before he is activated off the IL in the coming days. 

Alvarez has progressed well from a right-hand muscle strain that landed him on the IL on May 5. Manager Joe Espada said on Thursday that the slugger is "really close" to a return. That means fantasy managers could expect him back at some point during the team's weekend series against the Texas Rangers. 

Yordan Alvarez is “really close” and had “one of his best days,” Espada said. He needs a few more days.

— Brian McTaggart (@brianmctaggart) May 15, 2025

Given his injury and the slow start, Alvarez is a fantastic trade target to acquire. Although he is hitting just .210 with three home runs and 18 RBI in 29 games this season, his bat should heat up in the coming weeks once he returns. His expected slugging (.495), average exit velocity (94 mph), launch angle sweet-spot rate (40.5%), and barrel rate (11.9%) all rank extremely well in the early going. 

Therefore, Alvarez will eventually figure it out at the plate. He has been a little unlucky to start the season, and the three-time All-Star should once again finish with elite power numbers in 2025. The 27-year-old has hit at least 30 home runs and driven in over 85 runs in three consecutive years. 

Jack Flaherty, SP, Detroit Tigers

Detroit Tigers pitcher Jack Flaherty was always due for some regression following a fantastic 2024 campaign. The right-hander finished with a 3.17 ERA and 194 strikeouts in 28 combined starts for the Tigers and Dodgers last season. However, not many fantasy managers might have expected Flaherty to pitch this badly to start 2025. 

The right-hander currently owns a 4.61 ERA and 50 strikeouts in his first eight starts this season. Flaherty has also allowed at least four earned runs in three straight outings, which included giving up five runs across three innings in his last start against the Rangers on May 10.

There's no doubt it hasn't been the best start to Flaherty's year. His walk rate (8.1%) is up from last season, and opposing hitters have an expected .262 batting average against him. All this, though, makes the 29-year-old a sneaky buy in most fantasy leagues. 

The Tigers pitcher is still striking out batters at an above-average rate, and his expected FIP (3.35) is 162 points lower than his actual FIP (4.62). So, we could see better results from him on the mound over the next few weeks. Flaherty's 30.8% chase rate and 28.9% strikeout rate both rank in the top 17% of the league to start the season. 

Overvalued Fantasy Baseball Players to Trade Away

Trent Grisham, OF, New York Yankees

New York Yankees outfielder Trent Grisham has never been known as a strong hitter. Grisham has batted under .200 at the plate in three straight seasons and has failed to total over 15 home runs and 55 RBI in back-to-back years. Nevertheless, the 2025 season has been a completely different story for Grisham. 

He has been one of the most surprising hitters in baseball and will enter the weekend with a .283 batting average, 12 home runs, and 22 RBI across 36 games. Grisham's metrics also suggest that this is more than just a hot streak for the two-time Gold Glove winner. His expected slugging (.626), barrel rate (17.2%), and squared-up rate (33.5%) all rank extremely well to start the season. 

The concern is that playing time could eventually become a problem for Grisham in the coming months. Jasson Dominguez is starting to show signs of life at the plate, and Giancarlo Stanton (elbows) will see most of the designated hitter opportunities when he returns in the next few weeks. So, that really makes the 28-year-old a sell-high candidate in most fantasy leagues. 

AJ Smith-Shawver, SP, Atlanta Braves

Atlanta Braves starting pitcher AJ Smith-Shawver has been shoving on the mound over the past month. He has allowed just five earned runs across his last 30 innings pitched (1.50 ERA) to go with 30 strikeouts and an impressive 0.97 WHIP.

In his most recent outing on Thursday, the right-hander didn't allow a run across six strong innings against the Washington Nationals. 

AJ Smith-Shawver pitched well again today.

Today: 6 IP, 2 H, 0 ER, 2 BB, 6 K
Last 5 GS: 30 IP, 1.50 ERA, 0.97 WHIP, 9.4% BB, 25.6% K#BravesCountry pic.twitter.com/uuE57eMPrq

— Eric Cross (@EricCrossMLB) May 15, 2025

However, fantasy managers should be looking to sell Smith-Shawver in most fantasy leagues. His metrics don't really back up his strong numbers, and the Braves pitcher has faced the Nationals, Pirates, Reds, Rockies, and Rays during this five-game stretch. Four of those teams (Nationals, Pirates, Rockies, and Rays) rank toward the bottom of the league in runs per game, and the Reds rank 22nd in batting average (.236).

So, it's fair to say that Smith-Shawver has faced some easier opponents in recent weeks. Given that his expected ERA (5.13) is 280 points higher than his actual ERA (2.33), some regression should be coming for the right-hander. He also ranks in the 25th percentile or worse in average exit velocity (90.9 mph), hard-hit rate (49.4%), and walk rate (10.9%) this season. 

That means now is the perfect time to sell the Braves pitcher. Following another start against the Nationals on Wednesday, Smith-Shawver will face the Phillies, Red Sox, and Giants in three straight outings in Week 9 and Week 10. Therefore, see what you can get for a pitcher who should see his numbers regress over the next few weeks.

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