Dellin Betances' stuff is still there. He still has a mid-90s fastball. He still has a hammer curveball. And he still has a change-up he can mix in when needs to give the hitter a different look. 

All he's missing right now is confidence. 

That much was evident in his outing on Thursday during Trenton's 7-1 loss to New Britain. He fanned nine hitters in seven frames but came unraveled during a big sixth inning that, truth be told, didn't have to be so big. 

After a hiccup in the first, Betances mostly cruised through the next three innings. Then, with one out in the fifth, shortstop Addison Marsuzak booted a grounder. After a single put runners at the corners, Betances whiffed Aaron Hicks for what should have been the third out.

Instead, the Rock Cats reached Betances for three more hits (none of which were struck particularly hard), a run-scoring walk, a hit batsman and, ultimately, five more runs that put the game out of reach for the Thunder. Betances, obviously frustrated, slammed his glove on the top of the bench upon returning to the dugout.

"I was happy with my outing," Betances said, "but I was a little pissed off that fifth inning got a little bit carried away. I felt like I was in control the whole game. Other than than fifth inning and couple of mistakes up, I felt good."

This version of Betances looked eerily similar to the nights when Andrew Brackman, a former member of the Yankees' ballyhooed Killer B's, couldn't harness his stuff. When something didn't go Brackman's way, he wilted. Instead of re-grouping and focusing on the next man, Brackman kicked himself over the mistake, which usually only compounded the problem. 

Asked afterward how much of his struggles he believes are mental, Betances had this to say: 

"I feel good, so it's been a little mental. I think it's just a matter of repeating my mechanics when I'm in the game. My bullpens have been good, games I've had troubles. In Portland and today I felt real good. I felt, for the most part, like I was keeping the ball down. It was just that rough fifth inning."

It's clear, too, that the Yankees believe his struggles are mostly between his ears. The team's mental conditioning coach, Chris Passarella, was in the stands, and afterward two books from the team's mental conditioning department were on the kitchen island in the Thunder clubhouse. 

Those books were "Mind Gym: An Athletes Guide to Inner Excellence," by Gary Mack and David Casstevens (with a foreword by Yankees third baseman Alex Rodriguez), and "Coming Back Stronger: Unleashing the Hidden Power of Adversity," by Saints quarterback Drew Brees. 

Whether self-help books can clear Betances' head is anybody's guess, but at this point it certainly behooves the Yankees and the pitcher himself to give it a shot. He still has the body and the arsenal to be a major leaguer. The question now is: Does he have the mind?

Here are eight of Betances' nine strikeouts from Thursday evening: