"Thank God I had a mouthpiece in,'' Johnson said. "I couldn't feel my face. I was running back down the court and I was real dizzy. It made me realize this was a beast of a league.''
It was one of many "Welcome to the Big East'' moments for Johnson, whose indoctrination into the best conference in the nation is coming with a severe handicap.
Johnson, recruited as a power forward, says he is 6-6 "without shoes,'' and weighs 225 pounds. He does not possess the physical dimensions of a center in the Sun Belt Conference, let alone the Big East.
Even Rutgers coach Fred Hill said Johnson is playing "at a disadvantage,'' although it was one he gladly accepts because of extenuating circumstances heading into Tuesday's game at DePaul (9 p.m. tip).
When the season began, Johnson was slated to backup power forward Jonathan Mitchell. But when Greg Echenique was lost for the season with an eye injury, and with 7-foot freshman Brian Okam not nearly strong enough to play anything but a bit role, Johnson was shifted to backup starting center Hamady Ndiaye.
"It has to be frustrating because you're a 6-6 power forward, and you're guarding Samardo,'' Rutgers freshman wing Dane Miller said. "You get him one night, and come back the next and you're guarding (Cincinnati's) Yancy Gates. Then, you have to guard (Georgetown's) Greg Monroe, who is probably the best power forward in the conference, and then you have to guard (Notre Dame's) Luke Harangody.
"So, it is frustrating, and you're playing out of position.''
Johnson plugs along. His foul total (20 in 11 Big East games) nearly surpasses his point production (26).
His role is to provide Ndiaye with valuable rest time, and not allow the opposition to go on a bug run while Ndiaye sits on the bench.
"If it gets me on the floor, I've got to do it,'' Johnson said. "I thought when I was coming here I would be playing the four, but things happen. It's made me a better player, a more physical player.
"It's just complicated sometimes learning two spots.''
Johnson's biggest struggle is with physical nature of the position.
"You hear about guys being versatile and being able to guard the one through four,'' he said. "There's a reason that gets stopped at the four. Once you get to the five, it's like a grown man. People are so strong and so physical.
"You have to guard early before they catch the ball and push them off the block and up the lane, because once they catch the ball it's a harder job. I'm learning. I'm not going to block shots like (Ndiaye), but I can take charges and use my body to alter shots. I think once I catch on I can be effective at the five.''
Johnson is averaging 2.2 points, two rebounds and 11.6 rebounds per game in conference play, but his minutes are cut at both positions because Hill is shortening his bench.
Mitchell is averaging 33.7 minutes per game in Big East play. Ndiaye is averaging (31.6 minutes.
"He's done a lot of really good things, and I think he's going to be a heckuva good player for us,'' Hill said. "We just kind of put him at a disadvantage, and you might not really have seen the same potential we see in practice, come game time.
"Eventually, it's going to help him. But it doesn't help him right now. When you're not 100 percent sure of what you're doing, you can't play at a level that is instinctive and you want to play at. You're thinking too much instead of being reactive and playing the game.''