Britton spoke to Boone in the wake of giving up a walk-off, two-run shot by White Sox All-Star shortstop Tim Anderson in Chicago's 9-8 win over the Yankees in Thursday's "Field of Dreams" game in Iowa.
"I told him I don't deserve to be out there in the ninth inning; other guys deserve it," Britton said Saturday before Game 2 of the Yankees-White Sox series at Guaranteed Rate Field. "I haven't been pitching the way I should be to be out there when the team needs wins. I told [Boone] I want to pitch, whenever you need me I'll be ready, but I don't deserve to be out there in those situations."
Subbing in as the team's closer, and put in charge of the ninth inning with Aroldis Chapman on the injured list due to left elbow inflammation, Britton has had four save opportunities and converted only one. Britton has an 8.10 ERA in those four appearances, giving up three earned runs over 3⅓ innings pitched.
The left-hander has had subpar performances in his 11 appearances in save situations this season, accumulating a 7.45 ERA (8 ER / 9⅔ IP). And Britton's numbers are not remarkably superior in non-save situations, with a 4.50 ERA (3 ER / 6 IP) in such appearances.
"Physically [I am] not where I normally am at this stage of the season. But I have to find a way to get outs with where I'm at physically right now because it's just where I'm at," Britton said. "Just need to figure out how in the future I can get back to the top level of pitching that I want to be at."
Britton has been dealing with command issues, which he has attached to his routine being disrupted by missing spring training to undergo left elbow surgery. The 33-year-old also hasn't completely recuperated from suffering major weight loss after contracting COVID-19 in the offseason.
But with regard to COVID-19 and the surgery being factors affecting his performance, Britton called them "an excuse that's holding me back."
"I have to figure out a way to pitch with where I'm at. You've got to get outs, regardless of how you're feeling, velocity being down," he said. "I've been around long enough to know that it's not always about the best stuff, the most velocity, to get outs. It's about executing pitches. And I'm not doing a good job of that right now. And I'm capable of doing it."
Boone said he would likely lean on hard-throwing relievers Jonathan Loáisiga and Chad Green as his two main options for closing games until Chapman's return. On Saturday night, he turned to Green to close out a one-run game in the ninth inning, but the White Sox scored to send it to extra innings.
Britton came on in the 10th with the Yankees leading 7-4, allowing a run on two walks and an RBI single. He got only one out before Albert Abreu entered with the bases loaded and got the final two outs for his first save in the 7-5 win.
"It's going to be dependent on each and every night," Boone said of the Yankees' closer role, which he called a "fluid" situation. "But we'll continue to try and get Britt [Britton] into more situations where we feel like he can be really successful. He's going to play a huge role for us down the stretch here, and we have to get him back to that point all the way."
Boone also announced that injured starter Luis Severino, who did not pitch in his first rehab outing for Triple-A on Thursday night due to shoulder tightness, would undergo further evaluation on Monday, when he is scheduled for an MRI.
"[Director of pitching] Sam Briend noticed him trying to loosen up in his catch play, as he was getting ready to get on the mound," said Boone of Severino not taking the mound for his rehab start for Scranton/Wilkes-Barre. "Sam said something to him, and Sevy didn't really fight him on it; just wasn't feeling quite right. Ultimately, they pulled the plug on him making the start, probably wisely."
Boone admitted the situation was "very concerning" but refused to speculate on any possible setbacks in Severino's eventual return from Tommy John surgery, which was expected to be imminent.
"It's very concerning, when he's getting close to being back with us, and everything's gone really well. And enough for him to not make a start, it's obviously concerning," Boone added. "But at the same time, I don't want to speculate too much beyond him seeing the doctor and getting images and getting all the information. We'll hopefully have a clearer picture on Monday."
The Associated Press contributed to this report.