If you hadn't known Sean Manaea was a pretty good pitcher, you do now.

When the Oakland Athletics lefty no-hit the Boston Red Sox on Saturday, he threw a pure no-hitter. Only a couple of walks. No fluky runs scoring without a hit. Decent weather conditions. And you want to talk quality of competition? Manaea held the hottest damn team in the world without a hit.

There will be debate about this one, of course. First there was the Andrew Benintendi play that sent baseball fans and scribes alike scrambling for the pertinent rule book passages about running out of the baseline. Here, from Page 43 of the rule book, is that passage:

Rule 5.09(b)(1): Any runner is out when he runs more than three feet away from his base path to avoid being tagged unless his action is to avoid interference with a fielder fielding a batted ball. A runner's base path is established when the tag attempt occurs and is a straight line from the runner to the base he is attempting to reach safely.

The play: In the top of the sixth, Benintendi hit a slow chopper up the line that was fielded by Oakland first baseman Matt Olson coming in on the ball. Olson picked up the grounder and dove to tag Benintendi, who veered right -- with both feet clearly outside the outer edge of the running lane -- and then dove back into the first-base bag. Olson never tagged him. At first, Benintendi was called safe before the play was overturned.

Now, I am no rules wonk. And I will admit that the first time I saw the play, if I had been told that Manaea had lost a no-hitter in such a heartbreaking fashion, I probably wouldn't have thought much about it beyond the emotional aspect. However, the call was overturned, leading to widespread panic and to many of us combing through the rule book like we were characters from "The Paper Chase." Now that I have seen the letter of the law ... I think the umpires got it right.

A little while before that, I tuned the game in (I was following it as best I could from the press box at Guaranteed Rate Field in Chicago) and saw another play that might have given you pause. Sandy Leon looped a ball into shallow left that A's shortstop Marcus Semien pursued with his back to the ball and reached out to catch it wide receiver-style, only to see the ball pop out of his glove.

At first blush, I thought it was a hit. It was ruled an error. I haven't been able to find a replay, and there doesn't seem to be much of an outcry on social media. So I must deduce that the scoring call was fine.

The forensic part of our analysis complete, let's return the focus to Manaea and the amazing memory he just gave us in Saturday's 3-0 victory.

Manaea has been one of the American League's best pitchers in the early going, and on Saturday, he outshined one of the aciest of the aces we have right now in baseball -- the filthy lefty Chris Sale. He needed 108 pitches to do it and struck out 10.

Manaea now has a 1.23 ERA to show for his first five starts this season. That's the best in the American League among pitchers who don't play for the Houston Astros. (Ridiculously, Charlie Morton, Gerrit Cole and Justin Verlander are all ahead of him.)

Coming into the game, Boston was 17-2 with a plus-70 run differential and was on pace to score 1,049 runs this season. The Red Sox had won eight consecutive games and had scored 34 runs in their previous four outings. Then they ran into Mr. Manaea.

Manaea became the third pitcher to strike out at least 10 batters while no-hitting the Red Sox. You might have heard of the other two. If not, you can find their plaques in Cooperstown: Jim Bunning and Walter Johnson.

And if you're a Red Sox fan with some residual curse phobia left over from the pre-2004 days, here's a bad omen: No team since the 1988 Dodgers has been no-hit and then gone on to win the World Series in the same season.

But Saturday night wasn't about the Red Sox and their superstitions. It was about an emergent pitcher from a team on the left coast that plays in an often under-attended venue whom you should probably pay a little closer attention to.

His name is Sean Manaea, and he just authored the 297th official no-hitter big league history.