Asked what the problem might be, Zwinak -- described earlier this year by his high school coach as a good old country boy -- was typically reticent.
Just a bump, he said. Bruises.
You may take that for what it's worth, seeing as the Frederick, Md., native had offseason surgery on that same wrist, after breaking it in the Blue-White Game back in April. But his postgame comportment underscored that he is powerful, yet vulnerable. Talented, yet flawed.
Makes him a worthy poster boy for this edition of the Nittany Lions, which battered Purdue 45-21. Zwinak, who came off the bench for the fourth straight game, ran 26 times for 149 yards and three touchdowns. The starting tailback, Bill Belton, rushed 19 times for 81 yards and a TD of his own.
In all the Lions (6-4) picked up 289 yards on the ground, on 58 attempts. That's what you're supposed to do against the Boilermakers (1-9), for one of the many things they don't do well is defend the run; they began the day 111th among the nation's 123 FCS teams in that category.
Then again, they were also no better than 92nd in the country in (deep breath here) scoring offense, scoring defense, total offense, total defense, rushing offense, passing efficiency and pass-efficiency defense.
They were, in fact, dead last in scoring, at a mere 11.8 points a game.
But the Lions allowed a team that seldom scores to post its second-highest point total of the season. They allowed a team that seldom wins to hang around. There were some defensive breakdowns, and one huge special-teams gaffe late in the second quarter, when Purdue's Raheem Mostert returned a kickoff 100 yards for a touchdown.
Penn State -- like Zwinak, talented but flawed -- pulled away in the second half. With two games left (at home against Nebraska next week, at Wisconsin the week after) the Lions have assured themselves no worse than a .500 finish. On the flip side, they continued a maddening trend of alternating victories and defeats each week since their 2-0 start.
After Saturday's game, a reporter made the mistake of asking coach Bill O'Brien about how the team's morale might be affected by a big day running the ball. The coach seized on the word morale, saying it has never been a problem, that the team has been enthusiastic since he took over last year. That word, he added, gets thrown around like it's a cheeseburger.
Consistency is another matter. On Saturday the PSU lead was just 28-21 with 11:19 left in the third quarter, after the Boilers whisked 84 yards in seven plays upon receiving the second-half kickoff. Quarterback Danny Etling, who hit Deangelo Yancey for a gain of 45 during the march, capped it with an 11-yard run.
But the Lions' defense held the Boilers scoreless after that, forcing two fumbles in the process. (In all the Lions harvested three turnovers, matching a season high.)
The offense in the meantime reeled off the day's last 17 points, on Sam Ficken's 29-yard field goal, Zwinak's five-yard TD run and Christian Hackenberg's four-yard score on a bootleg around right end. The latter play was not without its humorous overtones, for O'Brien told his quarterback to keep the ball rather than hand it to Zwinak on a blast off the left side. No one else was aware that was going to happen.
I about had a heart attack, Zwinak said. I didn't know it. I turned around, looking for (the ball). I thought I missed it. But I then I saw him running with it. I was like, 'Thank god.'
His concern is understandable, considering his well-documented fumble problems. He lost one in the early season loss to Central Florida, another in the Oct. 12 victory over Michigan (leading to his relegation to the bench) and one more in the Ohio State debacle two weeks later.
That he has reemerged is in part due to Belton's own fumblitis. He put the ball on the ground two weeks ago against Illinois, and did so again on the first play from scrimmage during last week's loss at Minnesota. Zwinak came on to run for a season-high 150 yards against the Gophers, then spelled Belton after he coughed the ball up yet again in Saturday's second quarter, with PSU leading 14-7.
It's frustrating, O'Brien said, because they're good players. They're great kids. They're better kids than they are players. We'll continue to work with it. You don't want to overemphasize it, because then you have the guy thinking about it all the time. But we have to stop putting the ball on the ground. That's the bottom line.
In this case the Lions escaped unscathed, as cornerback Jordan Lucas intercepted Etling and returned it 22 yards, with a personal foul tacked on as well. Zwinak accounted for all the yards on a 33-yard mini-march, including the last one.
Hackenberg (16-for-23, 212 yards, one interception) found fellow freshman Adam Breneman for an eight-yard TD late in the first half -- Breneman's first career score -- to make it 28-7. But the TD by Mostert came 1:05 before intermission. Then Etling scored early in the third quarter.
The Lions kept pounding away, though, the 6-foot-1, 240-pound Zwinak in particular. Yes, he fumbled again -- this time a teammate recovered -- but he was a game-long force, as was his line.
That was a real fun game for us, with respect to just coming off the ball and hitting plays, guard John Urschel said. The offensive linemen, we really enjoyed it -- especially the inside three.
You walk back to the huddle and you're talking to the other offensive linemen, Howle said. You're like, 'Hey man, how'd you do on that play?' 'Good, I got a pancake.' We're chatting it up and we're really excited and having fun. That's what we did today.
Presumably Zwinak did as well, though the good old country boy is not the demonstrative type. Nor was he about to discuss how he was feeling as he went through all his ups and downs over the last month. It's just come out, work every day, and take one day at a time, he said.
He's a kid, because he's so competitive he's hard on himself, linebacker Glenn Carson said. But he's able to get over that and just continue to work hard and practice hard and not let those things get to him.
After one game when he fumbled it, defensive tackle Kyle Baublitz said, everybody thought he would be down. But he came back and he persevered, and he went out there and proved people wrong, that he can still run the ball fast and physical.
Somebody suggested to Howle that Zwinak's approach is such that he could earn honorary status as an offensive lineman.
I'm sure he would love to, Howle said with a laugh, but I think there's a weight limit on that. I don't think he's hit it yet.
What he is, at the very least, is typical of this edition of the Nittany Lions -- powerful, yet vulnerable. Talented, yet flawed.