Bill Belichick has been coaching in New England for 18 seasons, and although he's watched his defense struggle several times throughout the years, no team has ever done to him what the Kansas City Chiefs did on Thursday. 

After Kansas City's 42-27 win, Belichick gave a pretty blunt assessment of his team's performance. 

"Bad defense, bad coaching, bad playing, bad football.," Belichick said. 

So just how bad was New England's defense?

The 42 points scored by the Chiefs was the most that any team has ever scored against New England in the Belichick Era. 

In 18 years, the Patriots have only given up 40 or more points a total of five times, and the Chiefs have done it twice in the past three years. The other instance came in 2014 when the Chiefs beat the Patriots 41-14 in a loss that gave us arguably the best Belichick phrase of all-time, "We're on to Cincinnati."

Not only did the Chiefs put up the most points of any Patriots opponent during the Belchick Era, but they also racked up the most total yards. Thanks in large part to Alex Smith's 368 passing yards, the Chiefs totaled 537 offensive yards in the game, which is the most the Patriots have ever given up under Belichick. 

Before Thursday, that honor belonged to Peyton Manning and the Broncos, who racked up 507 yards in the AFC title game following the 2013 season. The loss to the Chiefs marked just the fourth time that the Patriots have surrendered more than 500 yards under Belichick. 

Now you know why Patriots fans were looking so sad toward the end of the game. 

What Alex Smith did to the Patriots defense is something that almost never happens. With 368 yards and four touchdown passes, Smith became just the second quarterback to throw for 300 or more yards with four or more touchdowns and no interceptions against a Belichick defense. 

Smith joined Drew Brees, who threw for 371 yards and five touchdowns in a 2009 win, as the only other quarterback to torch a Belichick defense like that. 

As far as QB rating goes, Smith now has two of the top four games ever against a Belichick's Patriots. 

A big reason was Smith's numbers were so high is because he connected on two touchdown passes of more than 70-yards (75 and 78). To put that in perspective, the longest touchdown the Patriots gave up in 2016 came from only 26 yards away. That number got blown out of the water twice in one night, and we're only in Week 1. 

The sad thing for the Patriots is that we're not even to the ugliest part of the loss. The ugliest part of their defensive performance might be the fact that they gave up an NFL record to Chiefs rookie Kareem Hunt

Hunt racked up 246 yards from scrimmage (148 rushing, 98 receiving), which is the NFL record for most scrimmage yards for any player playing in their first career game. 

If you're scoring at home, the Patriots gave up the most points and yards they've ever given up under Belichick, an NFL record for most scrimmage yards by a rookie and they got torched by Alex Smith. 

Anyway, the big losers in all of this could be Saints. After getting throttled by the Chiefs in 2014, the Patriots went "on to Cincinnati" and gave the Bengals a 43-17 beatdown, and it wouldn't be surprising to see the same thing happen to New Orleans.