With the MLB All-Star break in the rearview mirror, teams are now gearing up for the second half of their campaign. Whether that means playoff contention or future scouting, fantasy baseball players should play attention.

Players around the league will find themselves in new opportunities. Especially after the trade deadline, the league could be flipped on its head. If a player is seeing more playing time or has moved up in the order due to these changes, they become even more valuable on the waiver wire.

The same is true for players who entered the break on a hot streak. Teams will want to see if their first half was a fluke. Their bat has earned them a spot in the lineup and could be the key to fixing your fantasy baseball lineup.

And of course, injuries will play a role. If a player in front of them goes down, maybe a player looked over on draft day gets the call. In that situation, the waiver wire allows you to add a player who could carry immense value without using a draft pick.

While it's already the second half, there's still plenty of baseball to play. Lineups, rotations and rosters will all change. But at least heading into Week 18, these four players would give any roster a boost heading into a hopeful fantasy baseball playoff push.

Every player on this list is owned in 30 percent or less of ESPN fantasy baseball leagues.

Clayton Kershaw, SP – Los Angeles Dodgers

Los Angeles Dodgers starting pitcher Clayton Kershaw (22) throws to the Arizona Diamondbacks in the first inning during Game 1 of the NLDS at Dodger Stadium in Los Angeles on Oct. 7, 2023.
Rob Schumacher/The Republic / USA TODAY NETWORK

One player on this list who will undoubtedly break that 30 percent threshold is Clayton Kershaw. While he fits the parameters for now, his inclusion is mainly a reminder that the future Hall of Famer is soon set to make his 2024 debut.

Kershaw has missed the entire campaign as he works his way back from shoulder surgery. But he looked impressive over three rehab starts, pitching to a 3.60 ERA and a 12/2 K/BB ratio over 10 innings. Manager Dave Roberts has already confirmed that Kershaw will start on Thursday against the San Francisco Giants.

Over his 24 starts in 2023, the left-hander held a 13-5 record with a 2.46 ERA and a 137/40 K/BB ratio. He earned the 10th All-Star nomination of his career, to go along with an MVP, three Cy Youngs and a host of other accolades.

With his shoulder injury behind him, Kershaw is ready to help lead the Dodgers to the World Series. It isn't often a player of his caliber is available off waivers as late as Week 18. It should be the final week Kershaw is readily available for free.

Lawrence Butler, OF – Oakland Athletics

Oakland Athletics' ownership seems more focused on their move to Las Vegas rather than fielding and building a contending team. Still, Lawrence Butler has given Oakland plenty of excitement, for the last time before their franchise-changing move.

However, his breakout didn't come until after his return to the majors. A slow start got him sent back down to Triple-A in May. But since getting recalled on June 18, Butler is hitting .298 with seven home runs.

Over his last 20 games, Butler has a .339 batting average with seven home runs, 23 RBI and three stolen bases. His hot streak has moved him to the top of the lineup. While it may be the Athletics, being any team's leadoff man is sure to produce some fantasy baseball value.

Butler is still batting just .230 on the season. But he is on a tear right now and makes for a strong waiver wire addition as long as his bat is hot.

Spencer Schwellenbach, SP – Atlanta Braves

The Atlanta Braves were forced to place Max Fried on the injured list with a forearm injury on Sunday. While Spencer Schwellenbach was already a part of the rotation, he should get an even greater opportunity in the wake of Fried's injury.

Over his first eight games at the major league level, the right-hander has pitched to a 3-4 record with a 4.43 ERA and a 41/10 K/BB ratio. His last two outings has shown Schwellenbach has what it takes to remain at the major league level.

Against the Philadelphia Phillies, the righty threw six innings, allowing one run while striking out six and walking none. He followed it up by throwing seven innings of one-run baseball against the San Diego Padres, striking out three and walking one. The Braves won both contests.

Atlanta will now get a long look at what Schwellenbach has to offer. Coming off two standout starts, Week 18 makes for the perfect time to add him off of the waiver wire.

Juan Yepez, 1B – Washington Nationals

Washington Nationals first base Juan Yepez (18) celebrates in the dugout after hitting a three run home run against the Cincinnati Reds during the fifth inning at Nationals Park.
Geoff Burke-USA TODAY Sports

After showing some fight early, the Washington Nationals have essentially fallen out of the playoff race. However, they seem to have found a diamond in the rough through first baseman Juan Yepez.

In the 12 games since joining the Nats, Yepez is hitting .378 with a home run, six RBI and a stolen base. One July 19, he hit his first home run of the season, driving in three runs in a victory over the Cincinnati Reds. He hit third in the lineup, a spot he has become accustom to. Yepez's power leads him to slot no later than fifth in the Nationals' lineup.

There is a bit of risk to his pickup. He is a career .257 hitter with 15 home runs and 38 RBI to his name. Twelve of those home runs and 30 RBI came when he was a rookie on the St. Louis Cardinals. But the season after, he hit .183 with two home runs and two RBI.

But fantasy baseball is all about finding trends and riding the wave. Yepez has created a seismic shift and has been a dominant force for the Nationals. If your team is in need of some extra hitting, Yepez has proven he's here to help.