The San Francisco 49ers’ receiving core took a significant blow today as veteran wide receiver Michael Crabtree tore his Achilles tendon. 

Crabtree underwent surgery today to repair the tendon and is expected to miss at least six months. Although there is a possibility that Crabtree can make a comeback this season, any help that he may be able to provide to the 49ers would likely not come until mid-November, at the earliest, and is not guaranteed. 

The 49ers will benefit even more now from the off-season acquisition of Anquan Boldin, who becomes more important than ever in a 49ers receiving corps that now lacks Colin Kaepernick’s favorite target.

Last year’s first round draft pick A.J. Jenkins, who played a total of 35 plays last season for the 49ers, is one possible option to replace Crabtree on the depth charts. For Jenkins to take advantage of this opportunity, it is crucial that he shows improvement in his game and maturity during the off-season workouts as Jenkins did not have a single reception last season.

Mario Manningham is recovering from tears to his left ACL and PCL suffered in Week 16 and it is unknown how much he will be able to contribute this season. He remains on the roster after taking a pay cut to secure a contract for the 2013 season. If healthy, Manningham could help fill some of the void marked by Crabtree’s absence.

Another option would be for the team to re-sign veteran receiver Randy Moss, who expressed after the Super Bowl that he had a desire to come back. The 49ers decided to let Moss go after the season, but may want to take another look at him with Crabtree out. 

Further utilization of tight end Vernon Davis in the passing game is a possibility, as Kaepernick and Davis appeared to develop a good amount of chemistry with one another in last year’s playoffs. Davis’s speed at the tight end position allows him to line up as a wide receiver, and the investment of a second round draft pick on tight end Vance McDonald may allow the Niners to utilize Davis as a receiver in two tight-end sets.

Crabtree’s injury also gives the 49ers incentive to take a longer look at this year’s fourth round pick, Quinton Patton. Patton, however, appears to be a work in progress at this point, and his chances of taking over Crabtree’s spot in the receiving corps, at least early in the season, appear slim. 

According to Rotoworld, Terrell Suggs and Da’Quan Bowers suffered similar injuries last season and were able to play by mid-October. However, their injuries occurred earlier in the spring than Crabtree’s and the “start-and-stop nature” of the wide receiver position may make Crabtree’s ability to make a full recovery and be effective in the receiving corps more difficult.