There’s nothing worse for a contending team trying to make the playoffs than your sure-thing, lights-out set-up man suddenly posing as a mortal.

You expect him to be your rock, the shut-them-down, nail-in-the-coffin guy who will protect and preserve things before handing it over to the closer.

The Daniel Bards and Jonathan Papelbons of the baseball world often separate the good teams from the bad teams. Surely they have a big say in how far into the playoffs the team goes.

But since Aug. 1, Bard has not been Bard. He has made 15 appearances since then and allowed 13 earned runs in 15 1/3 innings (8.07 ERA). He doesn’t resemble himself. It looks as though Matt Albers or Dan Wheeler has invaded his body.

Not what you’re looking for in mid-September with the Rays coming in for four games.

“Yeah, struggling with timing and with my delivery,’’ Bard said after allowing three runs (two earned) in the eighth inning yesterday while failing to protect a 4-2 lead.

“I can feel it on every pitch. Feels a little different. I’ve been through it before. I think the effects of it are just magnified by how big these games are.

“Sometimes you go out there and your mechanics are a little off and they swing at a couple of pitches and you’re able to get through it. Unfortunately they really haven’t been doing it.’’

He walked Edwin Encarnacion and Kelly Johnson to start the eighth. Normally, Bard has the strikeout pitch to overcome such a poor start.

But his own throwing error on a bunt loaded the bases, and then a ground out and a two-run single by Adam Loewen resulted in three runs.

That was Toronto’s margin of victory in the 5-4 win.

In his last three appearances, Bard has allowed eight earned runs in 2 1/3 innings. In nine games against Toronto this season, he has a 7.71 ERA.

“You guys haven’t seen me do it much up here because it hasn’t happened much, but I’ve had it happen before and I’ve gotten through it,’’ he said of his mechanical glitch. “Like I said, it’s been magnified by the hitters’ approach to the location of the pitches.

“Something I’ve fixed before and I’ll fix it again. It’ll take the next couple of days to put in the work and get timing in my delivery again.’’

How will he fix it?

“Usually, repetition,’’ said Bard. “Talking to the people who know my delivery best and see what they’re seeing now and seeing when I’m at my best.

“[Coach Gary] Tuck has seen me as much as anybody in this organization and has seen me at my best and when I’m struggling. He sees every warm-up pitch I throw. Me and Curt [Young], we’ll talk about it.’’

Bard understands his importance to this team. Without him, it doesn’t work. Already, the Sox are trying to figure out the sixth and seventh innings. Albers has been ineffective. Alfredo Aceves can’t be pigeonholed into a specific inning because he’s such a jack-of-all-trades type.

Bard has been seen as the heir apparent to Papelbon. But will he be?

“I haven’t watched the video of this outing, but pitching is such a feel thing,’’ said Bard. “Sometimes, the mistakes, you get away with, and sometimes they’re magnified.’’

When the mechanics go, the confidence goes. Late-inning relievers need that confidence.

“I think it starts with mechanics getting a little bit out of whack,’’ said Bard. “Any time you’re thinking about mechanics, it’s not a good thing. When they’re out of whack, you have to do things to straighten them out.

“As soon as I get back to the fluid delivery I’m used to - and it’s probably going to look the same to you guys, going to be some minor tweaks that only I can feel - but you’ll notice it by the way the ball is coming out of my hand.’’

Young, the pitching coach, didn’t seem worried about getting Bard back on track.

“He’s got a nice checkpoint with his delivery,’’ said Young. “We’ll get back on that tomorrow.

“He’s a guy that will bounce back. His arm’s feeling great and healthy. We’ll get it back going in the right direction.’’

Is Bard tired?

“Everybody is beat up physically a little bit,’’ said Young. “The season is so long. You play 162 games. Sometimes it shows up physically at the end as well as mentally. We’ll get back on it tomorrow and he’ll be fine.’’

“Right now, the fastball command is certainly an issue, and it’s getting him in trouble,’’ said manager Terry Francona. “His fastball is kind of cutting on him a little bit. Probably when he’s not trying to.

“We’ve got to get him back to being the Bard we all have come to trust because he’s such an important part of what we’re doing.’’

Regarding Bard’s previous outing in Tampa Bay (one-third of an inning, two hits, one run), Francona said, “I thought the other day he got a little low on his arm slot. I didn’t think that today. Even on that throw to first, he kind of cut it a little bit. I’m sure confidence plays a part. That’s something we’re going to have to figure out in a hurry.

“We do everything we can. Try to analyze but not overanalyze. Be supportive. The one thing we don’t worry about is Bardo’s work ethic. He’s been a kid that’s been there before.

“He’ll figure it out, with help if he needs it. We’ll get there.’’

They’d better get there soon. There are a few players who, if lost, could send the season into a free-fall.

The Sox are getting one of them - Josh Beckett - back tomorrow night.

They’ve managed to keep the others - Jacoby Ellsbury, Adrian Gonzalez, Dustin Pedroia, David Ortiz and Papelbon - fairly healthy. Jon Lester has been strong except for his last outing vs. the Rays, when he lasted only four innings.

Now it’s Bard’s turn to figure out how to be himself again.

Nick Cafardo can be reached at cafardo@globe.com. Follow him on Twitter @nickcafardo.