The manager was left infuriated by the insipid nature of a 2-0 loss which inflicted a serious blow to Hearts' European aspirations. They now sit six points behind fifth-placed Hibernian and seven behind fourth-placed Motherwell with three matches remaining.
Jefferies digested the manner of the defeat over the weekend and has pledged to resolve problems, revamp his squad and ship players out if necessary in order to build a competitive team for next season.
"It wasn't acceptable and I've told the players that. But don't worry, next year we'll put it right," he said. "If they want to be part of it they need to get their fingers out between now and the end of the season.
"We made it easy for Motherwell, that's the bit that sticks in my throat. It's the application. We were nowhere near them, didn't show enough desire. All you can do is make players aware how big the game is, so I've got a clear conscience on that.
"We told them before they went out. Billy's gone over it, as has Lockie, because it's our job to do so. We told them it wouldn't be easy because Motherwell didn't deserve to be on a bad run, they had been playing well. You only needed to look at the previous time we played them to see the problems they gave us.
"They knew coming to Tynecastle was a big day for them too. They knew it could either be one point between the teams or seven. That's a big difference and they wanted it more than us.
"It's easy to say we came in at the right time to learn about the players. I learned more about them on Saturday, I can assure you. There were one or two things where I was thinking 'well, we'll see', but Saturday made up my mind.
"You have to take the responsibility. What Motherwell have is players with good touch and movement and a bit of strength and movement. We never had anything like that. We were too easily brushed off it, sometimes we got a break or two but overall it was pretty poor stuff."