Red Sox manager Alex Cora, center, removes Chris Sale, left, during the sixth inning of Boston’s 9-6 loss to the New York Yankees at Fenway Park on Sunday night. The Red Sox have gone just 8-13 (.364) in Sale’s starts after going 18-9 (.667) in his starts last year. AP Photo/Michael Dwyer

Never has it been more clear than it was Sunday night at Fenway Park: the single biggest difference between the 2018 and 2019 Boston Red Sox is Chris Sale.

After the Red Sox started a key divisional series against New York with the three loudest wins of the season by a combined score of 38-13, Sale took the mound in front of a sellout crowd and national audience on ESPN, held the ball in his left hand and lobbed it over the plate.

With a chance to sweep and provide momentum the Red Sox haven’t had all season, Sale threw batting practice for the Yankees.

Control issues resulted in some costly walks and a pair of hanging pitches as the Yankees smoked Sale for six runs on their way to a 9-6 win.

“Without me, we have a pretty good chance to win this game,” Sale said. “That’s the toughest part.”

The problem for Sale wasn’t velocity. All season it’s been about 2 mph slower than it was last year before his shoulder injury, and he’s had various levels of success. Despite a fastball averaging 94 mph, he entered Sunday’s start with 22 strikeouts in his last two starts, a pair of gems in which he allowed two total runs.

Sunday, his fastball sat at 93 mph and his slider at 79 mph, though the location of the pitches was much more the focus.

After striking out three in the first two innings and looking strong, Sale walked the eight-hitter, Cameron Maybin, then served nine-hitter Austin Romine a juicy changeup right down the middle. Romine destroyed it over the Green Monster for a two-run shot as the Yankees took an early lead.

The very next inning, Sale lost command again, this time walking Luke Voit and then lobbing a slider down the middle for Didi Gregorius, who smoked it into the right-field bleachers for another two-run shot.

“It just seemed like my stuff flattened out when I got out of the stretch,” Sale said. “That’s when they did all their damage. It just seemed like when I was in the windup, I had a good rhythm. Once I got in the stretch, it was a little different ballgame.”

Sale has allowed 20 homers in 129 innings this year after allowing just 11 homers in 158 innings in 2018.

Two more runs scored to Sale’s name in the sixth before he finally departed with his team in a 6-2 hole.

“He walked two guys and he hung three pitches, it happens, you know?” said Red Sox Manager Alex Cora. “But the walks were the one that put him in a bad spot.”

Sale fell to 5-10 with a 4.26 ERA this season. The Red Sox have gone just 8-13 (.364) in his starts after going 18-9 (.667) in his starts last year.

“It’s tough, I’ll be completely honest with you guys,” he said. “I have nothing to shy away from. I’m at a point where it’s been a tough year. Up to this point it really has been a grind. I know what I’ve done in the past, I know who I’ve been and what I can do.”

If the 2019 Red Sox had the same winning percentage with Sale on the mound, they’d have seven more wins with a 66-41 record, on pace to go 100-62. Instead, they’re 59-48 and on pace for 89 wins.

“I think my momentum really means nothing without the team’s momentum and we had a lot going into tonight,” he said. “I could take pitching bad and still winning a game or giving my team a chance to win, but I really kind of sucked the life out of us today. And was kind of the deciding factor. That’s kind of the toughest part is being in a position to really kind of put the dagger in and just kind of leaving the door open.”

The starting pitching is what carried the team last year. It hasn’t been nearly as consistent in 2019.

Their ace has been anything but.

“Now is not the time to start dragging or hanging our head or anything like that because it’s only going to get worse,” Sale said. “We have the most important baseball coming up right now. So, I don’t have time to sit around and pout or hang my head or go out there and not try to compete. That’s the deciding factor. I still have a job to do and I’ll be the same guy I’ve always been.”