Wide receiver Brandon Carsell automatically reverted to the 49ers' injured reserve list after he cleared waivers on Wednesday.
Carsell, who had a brief stint on the Raiders' practice squad as a rookie last year from USC, sustained a torn ACL in his right knee early in his first practice with the 49ers on June 12 after he was added to the team's 90-man roster as a free agent.
Carsell was the second 49ers player to sustain a season-ending injury during the team's offseason program. Fullback Alex Debniak (Stanford) sustained a torn Achilles on June 7. He was also placed on injured reserve after cleared waivers.
Neither Debniak nor Carswell counts against the 49ers' 90-man roster limit. Both players have split contracts in which they are scheduled to receive $288,000 apiece, rather than the rookie minimum of $405,000 this season.
The 49ers are leaving the door open for wide receiver Michael Crabtree, who sustained a torn Achilles on May 21. He underwent surgery the following morning. Crabtree is on schedule to resume walking in four weeks. The 49ers expect him to be available late in the regular season.
Under an NFL rule adopted last year, every team is allowed to designate one to return from injured reserve. Crabtree is likely to be that person.
The 49ers did not use the "designated to return" option last year, but coach Jim Harbaugh said he wishes the 49ers had kept the door open for veteran outside linebacker Parys Haralson, who sustained a torn triceps during the exhibition season and placed on season-ending injured reserve.
Haralson remained close to the team last year and assisted his teammates on the defensive side of the ball while going through his rehab daily at the team's practice facility. As it turned out, he could have returned late in the season, Harbaugh said.
"I know one of the things I look back and think that I made a mistake on personally was probably not putting that tag on him, that exemption that he could have come back and played because he was healthy and ready to go probably mid-to-late December." Harbaugh said.