The Cubs’ pitching staff took another hit in California.

They’re hoping they can strike gold with another reliever to make up for it.

Javier Assad, one of the Cubs most dependable starters this season, is landing on the 15-day IL with right forearm extensor strain. The Cubs signed right-handed reliever Vinny Nittoli to a major-league deal to take Assad’s role on the active roster. Nittoli, 33, was designated for assignment by the A’s over the weekend and elected free agency after posting a 2.25 ERA in 8 innings this season.

To make room on the 40-man roster for Nittoli, Yency Almonte was transferred to the 60-day IL. Almonte experienced some discomfort in his last live batting practice session and is getting a second opinion on his right shoulder strain.

The Cubs hope the right-handed Nittoli can be a solid bullpen piece much like Tyson Miller has been this season. Miller was designated for assignment by the Mariners and the Cubs traded minor leaguer Jake Slaughter for him. The righty has been one of the Cubs’ best relievers this season, posting a 1.62 ERA in 15 games since being acquired. He’s the only reliever in the Cubs’ bullpen with a sub-2.00 ERA and only Porter Hodge (2.00 ERA in 9 innings) and Keegan Thompson (3.50 in 18 innings) have an ERA below 3.50.

Assad had been one of the best pitchers not only for the Cubs, but in all of baseball to begin the year. Through his first 9 stars, the righty had a glistening 1.49 ERA and was pacing the Cubs’ rotation along with rookie Shota Imanaga.

But the 26-year-old has hit some bumps since tossing 6 shutout innings against the Braves on May 15. In his last 7 starts, Assad has a 5.19 ERA in 34.2 innings and opponents have a .914 OPS in that stretch.

With Assad’s injury, the Cubs will likely turn to righty Hayden Wesneski to fill his spot in the Cubs’ rotation. Wesneski made a spot start Wednesday in San Francisco in a bullpen game for the Cubs — he allowed 3 runs on a pair of home runs in 4 innings of work while striking out 7. The 26-year-old has made 21 appearances this year, with 4 starts.

The right-handed Wesneski originally started the season in Triple-A as a starter. After the Cubs sustained injuries to their rotation, he and rookie Ben Brown were recalled to make those starts. But Wesneski eventually found a home as a reliever and had been used in some leverage situations by manager Craig Counsell.

Nittoli was signed by the Cubs ahead of the 2023 season as a non-roster invitee. He pitched 3 scoreless innings for the Cubs in Cactus League play before being optioned to minor-league camp. He made 16 appearances last season for the I-Cubs, posting a 3.48 ERA and 1.21 WHIP in 20.2 innings before being traded to the Mets in June for future considerations.

Almonte, 30, will be eligible to come off the IL on July 7. Even without a second opinion, that date would have been right around when he would be ready to come back, at the earliest, so moving him to the 60-day IL allows the Cubs some flexibility with their 40-man roster.