Sunday was not a celebratory occasion for the New England Patriots. The Pats were destroyed by the San Francisco 49ers in one of the largest home defeats in the Bill Belichick era. Quarterback Cam Newton struggled before being replaced by Jarrett Stidham, and the Niners offense constantly confused New England's defense with a series of zone runs and quick-hitters.

New England has also reportedly lost linebacker Brandon Copeland for the season.

According to Pro Football Talk, Copeland has told teammates he suffered a torn pectoral muscle against the Niners and will miss the remainder of the year.

Copeland had been more of a special teams ace for the Patriots this year, though he did see his share of defensive snaps.

Regardless, Copeland's injury underscores some of the losses New England has sustained this season. Rookie safety Kyle Dugger did not play on Sunday because of an ankle injury. Meanwhile, wide receiver N'Keal Harry and offensive guard Joe Thuney both suffered injuries against the Niners.

Things have spiraled for the Pats in recent weeks. New England could not generate any offense in Week 6 against the Denver Broncos, though Denver's defense has been one of the toughest in football this season.

However, Newton and Co. struggled to move the ball against an injury-riddled Niners defense on Sunday, and New England's own defense could not stop San Francisco's punishing ground attack.

The Patriots (2-4) are now a full game back of the Miami Dolphins for second place in the AFC East, and 2.5 games back of the first-place Buffalo Bills.

Bill Belichick's team will have to fully buy into the “Do Your Job” mentality to get back on track, especially with injuries popping up.