Fields rejected five shots - just one off the single-game program record - in Wednesday night's 75-53 drubbing of LSU. Three of those came in the first 20 minutes, helping Tennessee forge a 43-27 lead.
Fields says the secret to his shot-blocking prowess is simple.
"Just timing," he said. "It's being the second guy off the floor (after the shooter already left his feet) so you won't get in foul trouble."
This strategy worked beautifully at Wilmington, where Fields blocked a school-record 59 shots in 2009-10. And it's working well at Tennessee, where he has 30 blocks in the first 20 games, despite averaging just 14 minutes per contest.
Senior point guard Melvin Goins says playing perimeter defense is a lot less nerve-wracking when you know Fields can neutralize your mistakes.
"It's a comforting feeling to know that if you overcompensate or if you gamble you've got a guy back there that can clean up the glass or at least make somebody alter their shot," Goins said. "He's a real good guy to have down there. He had five blocks, which was amazing. He also got a lot of extra possessions for us by getting his hands on some (passes). He's a good guy to have."
Sophomore wing Skylar McBee also feels freer to take chances on the perimeter because of Fields' presence under the basket.
"It's a huge confidence boost," McBee said. "John is great in that aspect of the game. He's really good at timing his jump and getting a piece of the ball."
Not all of Fields' rejections come at the expense of opposing guards, of course. He swatted away two shots by 6-9, 225-pound LSU center Malcolm White in the opening minutes of Wednesday's game.
"I feel like I had two good shot-blocks against White by being the second guy off the floor and not getting the contact," Fields said. "Then there was one later on in the first half when he was coming down the lane and I was hoping he'd put that one up because I really wanted that one."
Fields' fondness for swatting shots is obvious. He literally beams when he sees an opponent going up in his vicinity. Heck, he beams when he merely talks about blocking a shot. Clearly, it means a lot to him.
"Yeah, it is one of the biggest joys of the game for me," he said, grinning broadly. "I really hadn't had too many opportunities to block shots here lately but they (LSU Tigers) were aggressive going to the rim, and I was happy to meet 'em there."
Fields' aggressive defensive play around the basket eventually convinced LSU's players to quit testing him.
"Yeah," he conceded. "Sometimes in the second half they had a clear shot to the rim but they would pump-fake and then dish, instead of taking it all the way to the rim."
Fields isn't much of an offensive threat but his dynamic defense has earned him five consecutive starts. He wears out opponents with his energy, then 6-10, 270-pound Brian Williams comes off the bench to pound them with heft.
After conceding that starting is "different," Fields added: "I think I've adapted good. I think this system is working good - keeping Brian fresh for the end of the game and keeping him out of foul trouble. I feel like I'm playing my part and playing my role."
He'll get no argument from the LSU Tigers.