The Fantasy Baseball season marches on as we are nearly a third of the way through the 2023 regular season. Whether you're dominating, contending, or struggling to hold on, fantasy baseball trades are a surefire way to improve your roster. Figuring out who is over and underachieving is the key to figuring out the top fantasy baseball buy and sell options. Thankfully, we have you covered with five players you must buy/sell in Fantasy Baseball ahead of Week 8.

2023 Fantasy Baseball: Buy/Sell Trade Targets for Week 8

Buy: George Springer | TOR OF

.227 AVG | 5 HR | 16 RBI | 6 SB

George Springer was going as a top-20 outfielder and had an ADP of 63 in the Fantasy Baseball draft season. He's failed to return anywhere near that value thus far – ranking 50th among outfielders in ESPN's player rater. His struggles against righties in particular concerning with a paltry .217 average and 25 strikeouts in 129 at-bats. Yet, Springer is trending in the right direction of late. The 33-year-old recorded hits in 9/12 games thus far in May and has fallen victim to some incredibly bad luck. Springer has the ninth-biggest difference in his actual and expected WOBA (a stat cast measure of quality and amount of contact) in all of baseball. That carries over to his expected batting and slugging percentages which are both significantly higher than his actual ratios.

Springer continues to hit atop a loaded Toronto lineup that should keep producing runs at a high rate. Springer hasn't hit under .260 since his rookie season and has provided owners with some surprising production on the base paths despite his struggles. His six stolen bases put him on pace to crush his previous career-high of 16 and he should eclipse 20 home runs once he starts to heat up. Buy Springer on the cheap as a top Fantasy Baseball trade target heading into Week 8.

Sell: Nick Castellanos | PHI OF

.304 AVG | 5 HR | 25 RBI | 2 SB

This isn't to say that you should give away Nick Castellanos for nothing, but the Phillies outfielder is someone I'm looking to sell in Fantasy Baseball ahead of Week 8. Castellanos currently ranks as the No. 18 outfielder in roto leagues and sits all the way at No. 8 in points leagues. However, he is due for some regression with lower expected average and slugging numbers compared to his actual outputs. His numbers have begun to drop in the month of May after a hot start in April. Considering you likely didn't invest much to get Castellanos to begin with, now is the perfect time to sell him. He's the kind of player I would pair together in a 2:1 to acquire a struggling star considering you can likely fill his rest-of-season production off the waiver wire.

Buy: Hunter Greene | CIN SP

0-3 Record | 4.60 ERA | 1.58 WHIP | 12.3 K/9

The Fantasy Baseball community held high expectations for Reds starter Hunter Greene coming into the season. A former top-25 prospect, Greene compiled an ugly 5-13 record as a rookie last year but struck out 164 while walking just 48 in 125.2 innings. With a 100+ mph fastball, Greene looked like the next ace to come out of Cincinnati. That hasn't held true in 2023… yet.

Despite worse ERA and WHIP numbers this season, Greene's gotten unlucky. His xwOBA allowed of .321 is strong – ranking ahead of the White Sox's Dylan Cease and right behind the Astros' Framber Valdez. He ranks 14th in the league in strikeouts despite throwing fewer innings than anyone in the top 20. Pitching at Great America won't do him any favors, but the 23-year-old is someone who should only get better as the season goes on. I'd buy Greene as a top Fantasy Baseball trade target heading into Week 8.

Sell: Mitch Keller | PIT SP

5-1 Record | 2.38 ERA | 1.02 WHIP | 11.0 K/9

Look, I know what you're thinking. Mitch Keller has been nothing short of phenomenal this season. Through nine starts, Keller ranks as the sixth pitcher in ESPN's Player Rater and the second pitcher in points leagues. The Pirates' ace very well be in the midst of a breakout year in his fifth MLB season. Consequently, I have no doubt that Keller has taken a step forward and will likely be a top-30 pitcher the rest of the way.

However, fantasy baseball trades are about maximizing value. Keller holds an expected ERA of 2.90 and an expected slugging allowed of .339. Both of those are strong numbers but are nevertheless higher than his actual ratios. Although is only 27-year-old still, Keller held a K/9 under 8.5 in each of the last three seasons. He should be a quality member of any team the rest of the way but is unlikely to retain his current, top-five status. Don't give Keller away, but it's worth pulling the trigger if you can get a top-10 player in a position of need.

Buy: Josh Naylor | CLE 1B

.219 AVG | 6 HR | 26 RBI | 3 SB

To close things out, first baseman Josh Naylor is someone I'm looking to buy in Fantasy Baseball ahead of Week 8. Naylor has struggled mightily this season. However, he batted .256 with 20 HRs and 29 RBI last season. Yet, the Guardians as a whole have been abysmal on offense. After ranking 15th in runs last season, Cleveland sits at 28th this year. With essentially the same roster, the Guardians should pick things up as the summer marches on. As their No. 3 hitter, Naylor will reap the benefits. Naylor holds the largest difference in actual and expected average, slugging, and wOBA in the league – meaning he's been the unluckiest hitter in baseball thus far. Given the lack of depth at first base, Naylor is a top Fantasy Baseball buy heading into Week 8.