Editor’s update 4:16 p.m.: The 49ers announced on Tuesday that fullback Kyle Juszczyk has an MCL sprain injury and will miss four to six weeks. The team does not have a backup fullback. Even if they sign someone to play fullback, they would not be expected to fill the kind of role Juszczyk has played for the team. Instead, the team would likely move from a heavy I-formation rushing attack to more single back heavy rushing. It means more blocking work for the tight ends, which could potentially cut into George Kittle’s passing game work a little bit. Kyle Shanahan is a great offensive mind, but this downgrades Tevin Coleman and Matt Breida a little bit in fantasy football.

The San Francisco 49ers thumped the Cleveland Browns on Monday Night Football, thanks to a dominant defensive effort and a monster run game performance. Tevin Coleman, Matt Breida, and Raheem Mostert combined for 245 yards, averaging 7.2 yards per carry between the three of them.

A big reason for their success was the run blocking, and particularly fullback Kyle Juszczyk. The offensive line and tight end George Kittle contributed in a big way, but Juszczyk has emerged as the best blocking fullback in the league. And now, the 49ers might be facing some missed time due to an injury.

Juszczyk went down in the second half with what was described as a leg injury. It now appears to be a knee injury, with Tom Pelissero reporting it’s an MCL injury that requires an MRI to determine the extent of the damage.

Fantasy football analysis, San Francisco 49ers RBs Tevin Coleman, Matt Breida

The 49ers run game is rolling right now as they head to Southern California to face the Los Angeles Rams in Week 6. The Rams are struggling with consistency. They’ve ranked fared fairly well against the run, but are coming off a game in which Chris Carson ran for 118 yards on 27 carries.

The 49ers ran a fair amount of I-formation with their run game before Juszczyk got hurt. After he left, they went to single back sets and relied more on their tight ends. Kittle’s a strong blocker, but Juszczyk has been critical to the 49ers ground game. Kyle Shanahan is a great play-caller, but if Juszczyk misses Sunday’s game against the Rams, the run game gets downgraded a notch.

Coleman and Breida are still solid fantasy options, but don’t expect a pair of 100-yard games against the Rams in Week 6.