Even as all the signs of a big inning were showing themselves — Hanley Ramirez legged out a single, Travis Shaw laced a double to left, Jackie Bradley Jr. took an intentional walk from a reliever that wanted no part of him, and Blake Swihart worked a six-pitch walk with the bases loaded — Mookie Betts didn’t want to think too big when he stepped to the plate with the bases loaded in the seventh inning.

He went through all the normal thoughts.

Just have a good at-bat, he told himself. Extend the rally, he told himself. Get a good pitch, he told himself.

But he couldn’t help noticing what was developing, especially because over the past month, he’s seen it unfold so many times.

“I think if anybody was up at that point, you just kind of assume that something good’s going to happen,’’ he said.

It just so happened that he was the one who was up.

And when Indians reliever Joba Chamberlain left a thigh-high slider dangling over the plate, Betts launched it into the Monster seats for a grand slam that blew the doors open in the Sox’ 9-1 win Saturday afternoon at Fenway Park.

It was an exclamation point on a career day for Betts, who went 3 for 5 with two homers and a career-high five RBIs. But it was just another offensive avalanche for an offense that’s been furiously cranking out runs.

The Sox have homered in each of their last 21 games, they’ve scored 251 runs, the most in the majors, they’ve put up double-digit hits in 27 of their 43 games, and when he stepped back to take in the magnitude of it all, manager John Farrell couldn’t help but see a team that wasn’t just on a tear, but one that has the potential to be special.

The thought occurred to Farrell two weeks ago, when the Sox pumped out 40 runs in a three-game sweep of the A’s.

“That first came to mind in the Oakland series,’’ Farrell said. “Where not only did we do some things with the bat, the way we ran the bases, the defense that we played, there was a moment inside of those three games where you do kind of take a step back in the middle of an inning and you see what’s unfolding in front of us. Young, athletic, energetic players that are so in tune with what we’re trying to do as a unit. It is a powerful feeling when you get so many guys on the same page moving the same direction. You’ve got a potential for doing some special things.’’

On Saturday, there were almost too many special things converging to keep track.

After spending a month on the disabled list with a right shoulder impingement, Joe Kelly returned to the rotation and took a no-hitter into the seventh inning, overwhelming the Indians with a fastball that lit up the radar gun at 97 miles per hour.

“To walk out for the seventh inning, that’s probably a little bit unexpected when a guy’s coming back and making his first start,’’ Farrell said. “The fact that he’s got a no-hitter intact speaks volume to the type of stuff that he had today.’’

Jackie Bradley Jr. extended his hitting streak to 26 games when he shot a sharp ground ball up the middle in the sixth inning and sprinted down the line to spoil a diving play by Jason Kipnis and beat out a single.

Xander Bogaerts, who came in with the second-longest hitting streak in the majors behind Bradley’s, extended his streak to 15 with an RBI single in the third.

David Ortiz’s ground-rule double in the second gave him 601 for his career, tying him with Barry Bonds for 14th on the all-time list.

“We’ve just been grinding through at-bats for the whole game and we’ve been throwing the ball pretty well, too,’’ Betts said. “The defense has been pretty good at making the routine plays and some tough ones, too. If we can continue to do this for a while, we’ll be good.’’

Betts’s first homer — a solo shot in the fourth inning — barely sneaked over the Monster. When he got back in the dugout, he teammates had a few laughs about it.

Still, it was the third multi-homer game of his career. He’s hit safely in each of his last 11 home games. A double in the third made him the third Sox player this season to pick up three extra-base hits in a single game.

“To see our leadoff guy have that kind of extra-base capability, outstanding day by Mookie,’’ Farrell said.

Not even two weeks ago, Betts was half-joking about being surrounded by .300 hitters and how his average — Saturday’s three-hit day raised it to .276 — was bringing the team’s down.

He dug up some of the self-deprecating humor again after the win.

“Still, I think I have probably the lowest, but whatever,’’ Betts said. “I’ll just try and do something good every day whether it’s offense, defense, base-running, whatever.’’

Julian Benbow can be reached at jbenbow@globe.com. Follow him on Twitter @julianbenbow.