Yelich had missed two straight games with a lower back injury after leaving Friday's game against the Pirates early. The 22-year-old rookie was hitting .280/.365/.518 with seven home runs and 13 doubles in 222 plate appearances for the Marlins.
To take Yelich's place on the roster, Miami called up outfield prospect Jake Marisnick, who has hit .264/.306/.404 at Triple-A in 2014 after struggling during a brief spell in the majors last year.
Miami also placed Saltalamacchia on the 15-day DL on Monday. The catcher had missed all of June after suffering a concussion against the Braves on May 31. The 29-year-old Saltalamacchia has hit .237/.335/.404 with six home runs this season after signing a three-year deal with the Marlins this past winter.
Jeff Mathis and Jacob Realmuto will play at catcher while Saltlamacchia recovers from the injury.
Heaney promoted, Slowey and Wolf designated for assignment
The 23-year-old Heaney was ranked 30th among MLB prospects by both Baseball Prospectus and Baseball America prior to the season, both outlets also pegged Heaney as the No. 1 prospect in Miami's system. Thus far in 2014, he has excelled in four Triple-A starts after being promoted from Double-A in May.
Heaney has posted a 2.74 ERA with 27 strikeouts and just two walks in 23 innings at Triple-A New Orleans. He began the season by striking out 52 batters in 53 innings at Double-A, compiling a 2.35 ERA in eight starts and one relief appearance before moving up to New Orleans.
The left-hander combines a low-to-mid-90s fastball with a solid slider and changeup and has shown good control throughout his time in the minors. Heaney adds to a young Marlins pitching staff that has impressed in 2014 even after Jose Fernandez went under the knife for Tommy John surgery.
Designating Wolf and Slowey for assignment makes room for Heany and DeSclafani in the Miami rotation, and also adds further youth to the team's pitching staff.
Neither Wolf nor Slowey had made much of an impression for the Marlins this season. Wolf posted a 5.26 ERA in four starts, and Slowey fared even worse. The former Twins hurler had a 5.30 ERA but had been relegated to the club's bullpen since late April.
DeSclafani made his big league debut earlier this season when he made two starts for Miami in May. The right-hander allowed seven earned runs in 11.1 innings, striking out nine batters and walking two. Ranked No. 8 among Marlins prospects by Baseball Prospectus to begin the season, DeSclafani has a 3.92 ERA over 12 starts at Double- and Triple-A in 2014. In 64 innings in the minors, he has struck out 59 and walked 17.
With Heaney and DeSclafani in the fold, the Marlins now have four pitchers below the age of 25 in their starting rotation. Koehler, at 28, is the staff's elder statesman.