Newcastle capitulated 3-1 at Southampton on Saturday, their fearful defensive showing gifting the hosts a stroll to victory.
Benitez's attempts to insist Steven Taylor was withdrawn at half-time due to "stiffness" appeared little more than a benevolent act that failed to mask the defender's abject performance.
Shane Long, Graziano Pelle and Victor Wanyama consigned Newcastle to their sixth defeat in a seven-match winless run, leaving the Tynesiders six points adrift of safety with six games to play.
"Obviously we go into games a little bit scared and once we make the first mistake everybody loses the belief," said Benitez.
"And it's something that we have to change one way or another.
"Some of them I think they are strong enough mentally, but some of them need help.
"And we will try to help them one way or another. But we need to see which players we can count on and who can give what we are expecting."
Taylor stood motionless as Long strolled through to net Southampton's opener just four minutes in, before Newcastle allowed Pelle to double the lead under little to no resistance.
Daryl Janmaat's comical slip set Saints en route to their second goal, the full-back tripping himself up when he should have intercepted Wanyama's pass as a matter of course.
Wanyama's goal wrapped up Saints' victory inside the hour, just leaving Andros Townsend to fire a good-looking but meaningless riposte for Newcastle.
Taylor was withdrawn at half-time in a move that Benitez later insisted owed everything to a niggly injury.
In truth the Newcastle boss had no choice but to remove the 30-year-old whatever his injury status, given his calamitous performance.
Benitez admitted he was furious with his players at half-time, but insisted there will be no recrimination or finger-pointing as Newcastle target four wins from four home matches as an unlikely route to safety.
"Steven felt a bit of stiffness so I think it was a big risk to keep a player with problems on the pitch, especially with the problems we have in defence," said Benitez.
"So we had to change him, and that's it.
"At half-time, that could be the angriest I've been so far, yes. But it's not a question of shouting but saying the right things.
"You have to be upset, and I was really upset. I was telling them that the performance of the first half was not acceptable.
"We had to change and start with the commitment, passion and character, and after with the way we were playing.
"We had to change players, move some from one side to the other.
"It was obvious that we couldn't win with this mentality and playing in this way.
"My concern was I couldn't believe how we started the first half after the hard work that the players were doing during the week.
"The games at home are crucial for us. So we have to approach them as one.
"The confidence we must improve a lot, we have to get three points and that can change everything if we are capable of doing that.
"It's not the time to complain and blame each other, it's time to realise we have to stick together.
"We have four games at home and that is the key if we want to stay in the Premier League."