At the end of the day, the Boston Red Sox had every opportunity to win their 13-inning affair with the Kansas City Royals on Tuesday night at Fenway Park.

The Red Sox fell 7-6 after Eduardo Nunez flew out to the warning track in center field to end the game.

But if you ask manager Alex Cora, Boston was fortunate the game even went into extra innings.

“Awful,” Cora said after the game regarding the Red Sox’s defense, as seen on NESN’s postgame coverage. “That was an awful game, yeah. We were lucky we were playing 13 innings, honestly. That was bad. Mental mistakes, physical mistakes, all kinds of mistakes. That was awful.”

The Red Sox committed four errors in Tuesday’s loss, their first four-error game since last May 1.

Boston’s mental mistakes started early on when third baseman Rafael Devers booted a ground ball from catcher Salvador Perez that allowed him to reach to lead off the fourth inning. Perez then scored thanks to another error, this time on catcher Christian Vazquez, who lost the ball attempting to tag Perez on a sacrifice fly from Alcides Escobar.

The mental lapses continued in the 10th inning when Vazquez was called for the rarely seen catcher’s balk. The Sox backstop blocked a curveball from Matt Barnes and scooped the ball up with his mask. Luckily for Boston, that mistake did not cost the team a run.

The Red Sox are coming off a ridiculous month of April that saw them go 20-6 while playing crisp, fundamental baseball.

But in one May game so far, the Red Sox looked like a far cry from the team that started the year 17-2.

Here are more notes from Red Sox-Royals:

— The Red Sox now are 7-6 in games started by Sale and David Price.

— Craig Kimbrel gave up a game-tying home run to Alex Gordon in the ninth inning, his first blown save of the season The Red Sox closer was blunt about what happened in Gordon’s at-bat.

“I just made a bad pitch and he put it out of the ballpark,” Kimbrel said, as aired on NESN.

Kimbrel had allowed only one run in 11 2/3 innings on the season coming into Tuesday.

— Brian Johnson has given up nine earned runs in his last four-plus innings of work.

— The Red Sox are 4-6 in their last 10 games.