The New England Patriots are undefeated. But they’re not perfect.

The Patriots’ 16-10 win over the Buffalo Bills on Sunday at New Era Field marked New England’s ugliest performance of the season. New England had outscored its first three opponents — the Pittsburgh Steelers, Miami Dolphins and New York Jets — by a combined score of 106-17, yet Buffalo’s defense gave Tom Brady and Co. all they could handle in the Week 4 divisional showdown.

To say Cris Carter came away unimpressed with the Patriots’ offense would be an understatement, as the former NFL wide receiver-turned-analyst explained Monday on FOX Sports 1’s “First Things First” that New England has “serious, serious problems” despite improving to 4-0.

“I’m concerned about that offense,” Carter said. “You can only replace so many (players). (Patriots offensive line coach) Dante Scarnecchia’s gotten more shout-outs on this show than the guy that dumped (Jenna Wolfe) for the prom. We give him so much credit. But you need some talent to work with. You can’t lose your left tackle, again. You can’t lose David Andrews, which I believe is one of the most underrated football players — the center there in New England — that we have. And continuing to lose players. (Sunday) you could see, well, ‘what about Dont’a Hightower?’ When Dont’a Hightower went out of the game, you could run the ball through the middle of New England’s defense. It was a totally different defense. So that’s another injury that we must watch for.

“To me, this looked like Tom Brady in his first five years in the league. New England, brilliant special teams-wise. They get a blocked punt for a touchdown. Field position-wise, we know that. And this defense? It is nasty. Leads the NFL in sacks, they do not have one premier pass rusher, but they’re doing it with smoke, mirrors. They will crowd the line of scrimmage so bad that it confuses the quarterbacks. Now, let’s see later on when they get some veteran quarterbacks, can they keep it up? I know that secondary is the best in football, and Tom is playing to that.”

The Patriots’ defense — which didn’t allow a single touchdown in New England’s first three games — again stood tall, totaling five sacks and forcing the Bills to throw four interceptions (three by Josh Allen, one by Matt Barkley). New England’s offense managed just 224 total yards, though, with Brady limited to 150 yards through the air while completing only 18 of his 39 pass attempts.

“I had to ask myself (Sunday): If they’re playing against 30 other offenses, do they win that game? And I would say ‘no,’ because that was awful,” Carter said. “… New England, they do have some serious, serious problems. And that offensive line, you could see (the Bills) were getting to Tom Brady. And Tom Brady looked all of — how old is he? … Oh, he looked 42 (on Sunday).”

Thumbnail photo via Mark Konezny/USA TODAY Sports Images