The Bills (5-5), who benched Tyrod Taylor in favor of Peterman, lost their third consecutive games as they turned the ball over six times.
Peterman struggled in the opening quarter of his first National Football League start, throwing three interceptions - one of which was the result of a drop by fullback Patrick DiMarco.
The Chargers destroyed the Bills 54-24 in front of 25,015 fans at Stub Hub Center on Sunday afternoon. While the Bills know there is a risk in going to a rookie with the season on the line, they like what they saw out of Peterman in the summer and can go back to a more traditional offense now, having catered a lot of the packages to Taylor's strengths once their new regime opted to bring him back on a restructured contract.
With 1:51 to play in the third quarter, and the Chargers dominating, the L.A. defenders pinned their ears back on a pass rush.
The results of Peterman's first start were all too predictable.
LeSean McCoy finished with 114 yards rushing and two total touchdowns. As Peterman moved the Bills down the field, he threw a costly pass that was intercepted by Korey Toomer who took it 59 yards down the sidelines for a touchdown.
But Peterman threw his third interception to Tre Boston while getting planted on his back by Bosa, and Allen then caught his first touchdown pass since the Chargers' opener on a lovely back-shoulder throw by Rivers.
Rivers finally found his stride as he connected with a speedy Keenan Allen down the right side for the 21-yard touchdown and 17-7 lead in the second quarter. Bosa also forced a fumble while sacking Taylor on fourth down in the third quarter, and Melvin Ingram returned it 39 yards for a touchdown. His three interceptions in the quarter equaled Taylor's interceptions for the season.
The 135 points are the most points allowed over three games in franchise history.