The second half of the MLB season is underway, and with it comes an essential look at potential waiver wire adds for fantasy baseball enthusiasts. This week, focus on players under 40% rostered who could significantly boost your lineup as the season progresses. Luke Keaschall (MIN) is recovering from injury but showed promise in the minors last season with a .303 batting average and the ability to hit 15-18 home runs. Caleb Durbin (MIL) has turned around his season, hitting .324 with speed potential, while Austin Hays (CIN) is back from injury and performing well when healthy. Noelvi Marte (CIN) is making a comeback after a rough 2024, showcasing his power-speed blend. Zebby Matthews (MIN) is set to rejoin the rotation, and Quinn Priester (PIT) has been impressive as well. Finally, keep an eye on Shane Bieber (CLE) as he nears return from Tommy John surgery, making him a valuable stash option.