"I should have had 200 yards," McCoy said.
A go-ahead interception by cornerback Nickell Robey-Coleman, a late Tyrod Taylor touchdown pass and the running of McCoy lifted the Bills to a 30-19 victory over the Los Angeles Rams on Sunday at the Memorial Coliseum.
McCoy delivered his game-high rushing performance on 18 carries as Buffalo (3-2) captured its third consecutive decision. McCoy and the Bills took advantage of a Rams defensive line missing three starters, tackle Michael Brockers and ends Robert Quinn and William Hayes, due to injuries.
The Rams (3-2) had their three-game winning streak snapped.
"You always want to kind of finish a drive off with a touchdown, but a win's a win," said McCoy, who had two runs that led to Buffalo scores. "To get up here and nick-pick about this and that, come on, we got a 'W' against a good team (that) was a favorite."
Robey-Coleman, who played in the Coliseum for USC, put Buffalo up for good by picking off Rams quarterback Case Keenum and returning it 41 yards for a touchdown and a 23-16 Bills lead with 3:54 left in the third quarter. Robey-Coleman also intercepted Keenum on the Rams' final drive.
"That was a good homecoming for me. Today was a good day," Coleman said.
Coleman's pick turned the game around, but it was the Rams' failure to convert a fourth-and-5 situation at their own 23 with 3:47 left that cost them dearly. Los Angeles used a direct snap to wide receiver Bradley Marquez, but he failed to secure a first down after being stopped 3 yards short.
"We practiced it all week, we had the look and it didn't work," Rams coach Jeff Fisher said. "I'll take that. They executed in practice, they didn't execute it there. If that thing works, it's good stuff."
Earlier in the quarter, the Rams drove to the Bills' 4-yard-line and settled for a 22-yard field goal by Greg Zuerlein with 5:51 left, cutting the margin to 23-19.
Taylor connected with Marquise Goodwin on a 6-yard scoring pass with 2:37 to go, capping the scoring. Taylor finished 12 of 23 for 124 yards with a pair of touchdowns and no interceptions.
"Disappointing. That's a good football team, they're on a roll, but we have every reason to be OK with where we are right now," Fisher said. "I know there are a lot of teams that would like to be 3-2, but we still have work to do."
Zuerlein, who was 4-for-4 on field-goal attempts, nailed a 54-yarder to knot the score at 16-16 with 8:05 remaining in the third quarter. However, the Bills dictated the rest of the way.
"You can't miss opportunities," said Keenum, who completed 21 of 31 passes for 271 yards with no touchdowns and two interceptions. "And you can't turn it over. Every game comes down to one or two plays."
Keenum was sacked three times by Bills linebacker Lorenzo Alexander and four times overall.
Zuerlein's 37-yard field goal with 9:31 left in the first quarter gave the Rams a 3-0 lead.
The Bills then marched 76 yards in 12 plays, capped by a 4-yard scoring pass from Taylor to Justin Hunter for a 7-3 advantage late in the first quarter.
The Bills recovered a Todd Gurley fumble at the Buffalo 38 and turned it into a touchdown, needing only two plays to do so. McCoy's 53-yard romp set up Mike Gillislee's 5-yard scamper for a 13-3 Buffalo edge with 13:59 remaining in the second quarter. Dan Carpenter's point-after kick was blocked by defensive tackle Cam Thomas.
A 32-yard field by Zuerlein cut the deficit to 13-6 in the middle of the second period. Gurley's 1-yard run with 1:56 remaining in the quarter knotted the score.
Carpenter put Buffalo back on top 16-13 with a 23-yard field goal to end half.
Keenum is confident the Rams will bounce back.
"We've got a lot of football left," he said. "We have to keep fighting."
Gurley led the Rams' ground game with 72 yards on 23 carries. He also caught three passes for 36 yards.
NOTES: This was the first meeting between the clubs since the Rams recorded a 15-12 win in 2012. ... The Bills' inactives: QB Cardale Jones, CB Corey White, RB Jonathan Williams, G Gabe Ikard, C Patrick Lewis, T Cyrus Kouandjio and DT Marcell Dareus. In addition to DT Michael Brockers and DEs Robert Quinn and William Hayes, the Rams' inactives included QB Sean Mannion, RB Benny Cunningham, T Pace Murphy and WR Nelson Spruce. ... A crowd of 83,679 attended. ... Los Angeles visits the Detroit Lions next Sunday, while Buffalo hosts the San Francisco 49ers.