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FOXBOROUGH, Mass. — It was fun watching Aaron Rodgers against the Patriots, wasn't it?

Oh, wait.

That wasn't Aaron Rodgers. That was Alex Smith.

Are you old enough to remember when people were clamoring for rookie Patrick Mahomes? Like, five minutes ago?

Remember the knocks on Smith? Too safe. Too bland. The candy corn of quarterbacks. His greatest claim to fame was getting Wally Pipped by Colin Kaepernick in San Francisco.

Not horrible enough to lose games but not good enough to win them. And, mostly, didn't throw a good deep ball.

This isn't to say the Smith we saw in the Chiefs' stunning 42-27 win over New England in the season opener Thursday will be the one we see throughout the remainder of the year. Who knows what we'll see. All we know is that Smith shredded a Patriots defense which appeared damn near impossible to shred.

Alex Smith embarrassed a Bill Belichick defense.

"We had it handed to us on our own field," said Tom Brady.

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

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Brady said the Patriots lacked urgency. Smith played to score and win like his life depended on it.

For all of Smith's faults—and there are many—we saw Thursday that he can be aggressive offensively when his conservative head coach, Andy Reid, allows him to be. He can throw deep. He can be fearless. He can display mental toughness. He can, at times, do it all.

The Patriots did not allow a single catch of 75 yards or more last season. Smith threw two of them Thursday night, the most stunning of which went to Tyreek Hill.

With a weapon like Hill, we're going to see more of this from Smith. Last season, Hill had the two fastest times by a ball-carrier, according to the NFL's Next Gen stats, having reached speeds of 23.24 and 22.77 mph. (He may get competition this season from his new teammate, Kareem Hunt, who was fastest Thursday at 20.84 mph.)

The Chiefs' 42 points were the most the Patriots have given up in the 307 games of the Belichick era, regular season or playoffs.

Alex Smith did a lot of that.

Alex Smith, I said.

There was something dramatically different about Smith. According to ESPN Stats & Info (via ESPN's Chris Sprow), Smith had only two 75-plus-yard passing touchdowns between 2005 and 2016. He had two against the Patriots.

The weapons around him helped set the tone. Hunt set a league record for yards from scrimmage in his first NFL game with 246. The Chiefs defense was nasty, and the Kansas City offensive line physically destroyed the Patriots' defensive front. The Chiefs also effectively made tight end Rob Gronkowski disappear (two catches, 33 yards, no TDs).

Still, a lot of this was Smith. It takes raw talent to quarterback an offense that scores the most-ever points against a Belichick-coached Patriots team. Until Smith's 368-yard, four-touchdown performance, only one player had a game of 300 yards passing, four or more touchdowns and no interceptions against a Belichick defense, according to the NFL. His name is Drew Brees.

What Smith did was simple in theory, but it differed from the Chiefs' typical game plan during the Reid-Smith era.

Instead of sticking strictly to West Coast-style crossing routes and shorter throws, Smith threw deep. A lot. It was almost shocking to see, and it's something many people (including me) have wanted Reid to do.

The Chiefs now have so many weapons, Reid is almost forced to open things up.

Again, this was done against a Belichick defense, at New England. That's about as easy a feat as climbing a mountain.

After the game, Smith was calm and plain-spoken. His quotes didn't stand out, and he didn't look any different than he has before, save for the gorgeous suit that made him look like Bruce Wayne.

It all looked the same on the outside, but something was different. This wasn't the old Alex Smith. This wasn't the old, staid Chiefs offense that lacked imagination.

This was a different man. Maybe Kansas City's drafting of Mahomes lit a fire under Smith, or maybe Reid just finally relaxed.

If Smith stays this way, he'll be terrifying. That isn't a word generally associated with him.

Mike Freeman covers the NFL for Bleacher Report.