Get Globe sports news alerts right in your inbox

Xander Bogaerts had 14 hits in the first nine games of the season, nine for extra bases. When he broke a bone in his left foot on April 8 and had to go on the disabled list, the fear was that a promising season also had been fractured.

The Red Sox shortstop was hitting well last season until he was hit on the right hand by a pitch in early July. He returned too soon and struggled the entire second half.

The approach was different this time. As his foot healed, Bogaerts stood at the plate when teammates Rick Porcello and Eduardo Rodriguez threw in the bullpen between starts. That helped keep his eyes sharp.

Bogaerts also played in a game for Triple A Pawtucket then had to convince manager Alex Cora he was ready to return.

Bogaerts was activated last week and nothing has changed. His breakout season continued Monday night with a game-changing grand slam as the Sox came back from a three-run deficit to beat the Kansas City Royals, 10-6.

Bogaerts was 3 for 5 to raise his batting average to .412 and OPS to 1.171. He has 15 RBIs in 12 games.

Since coming off the disabled list, Bogaerts is 7 of 13.

“We’ve always known how good Bogey can be,’’ Hanley Ramirez said. “Now he’s showing everybody.’’

Mitch Moreland also homered and drove in two runs for the Sox, who collected 13 hits off three Kansas City pitchers.

The 21-7 Red Sox have won four of their last six games. Their 19 victories in April were a franchise record. Not since the 2003 Yankees has a team won 21 games before May 1.

Red Sox starter Eduardo Rodriguez had a dreadful 35-pitch first inning against the 7-21 Royals.

After Whit Merrifield reached on a bloop single, Rodriguez walked Jorge Soler, hit Mike Moustakas, and walked Salvador Perez to force in a run.

Rodriguez then walked Lucas Duda with one out to force in another run as rain fell and the crowd booed.

“I didn’t have command of the ball,’’ Rodriguez said. “That’s kind of frustrating for everybody.’’

When Jon Jay grounded to the right side, Eduardo Nunez couldn’t make the play as a third run scored.

The Red Sox started their comeback when Moreland (3 for 4, two RBIs) homered to right field in the second inning against Jason Hammel. Then came a five-run third inning.

With two outs and nobody on, Andrew Benintendi singled. Ramirez followed with a ground-rule double to right field as the ball got stuck under the wall.

J.D. Martinez and Moreland drew walks to force in a run and leave the bases loaded for Bogaerts.

Bogaerts worked the count full, fouled a pitch off, then got a two-seam fastball that stayed high in the strike zone. He unloaded, sending the ball high over the billboard closest to the foul pole in left field.

The shot was measured at 430 feet and left the bat at 110 miles per hour. Bogaerts faced the ball as he went down the line a few steps, but no Pudge Fisk body language was needed.

As the pitches added up, Bogaerts settled in until he got a pitch he could hit hard.

“You feel more comfortable,’’ he said. “That’s for me, I guess. Not saying you’re going to be successful when you put the bat on the ball. You just feel more comfortable seeing so many pitches.’’

At 25, Bogaerts has discovered his power with a more balanced setup at the plate. A positive mind-set has helped, too.

“Continue to focus on your swing every­ time in the cage,’’ he said. “Trusting it.’’

It was the sixth grand slam for the Sox, tying the 1996 Montreal Expos for the most before May 1 in major league history. The Red Sox record of 11 grand slams was set in 2005.

The Sox did not have any grand slams last season.

“I didn’t hit a grand slam in my career, by the way,’’ Cora said. “It’s not because of me.’’

True enough, Cora had 75 career at-bats with the bases loaded without a home run. But he was creative even then, getting hit by pitch five times.

Bogaerts is the first Red Sox shortstop with two grand slams in the same season since Nomar Garciaparra had two on May 10, 1999.

Handed a 6-3 lead, Rodriguez seemed determined to give it away. He hit Alex Gordon with one out in the third inning then gave up RBI doubles to Alcides Escobar and Merrifield on poorly located fastballs.

“It was a struggle for him,’’ Cora said.

With Rodriguez at 88 pitches, Hector Velazquez took over for the fifth inning, as Cora refreshingly did not chase a win for his starter.

Velazquez (4-0) threw two scoreless innings and struck out three. He dropped his earned run average to 2.05.

“I did feel we needed somebody else there in that spot,’’ Cora said. “He did an outstanding job. . . . He’s not just a guy in the bullpen. He’s very important for us. This guy can pitch.’’

Mookie Betts, who pulled his left hamstring on Saturday, sat out his second consecutive game. But he was available if needed and will probably start on Tuesday. Chris Sale is set to start that game.

Peter Abraham can be reached at pabraham@globe.com. Follow him on Twitter @PeteAbe.