"When you only have one guy who makes plays for himself and other people, it's tough to win," Penn coach Jerome Allen said. "We need other guys to step up and make plays. Outside of Zack, that's not happening. You're not going to beat too many teams at this level with just one guy making plays."
Rosen is just 6-foot-1 and he's fast, but not lightning. He has a good shot and a great sense for how to create space for himself and his teammates, and then decide which of them has the best chance to score.
If basketball is a game of will - and that's what it often comes down to - there isn't a player on the court who matches him. Unfortunately for Rosen and Penn, his great passes that should become assists and baskets aren't always converted by those around him. It must be frustrating, but he just shrugs.
"Part of the game," Rosen said.
Signing on with an Ivy League team comes with its own set of challenges and opportunities. Rosen is going to get a business degree from one of the great universities in the country. He's had the chance to travel the country, to be part of a great tradition, and, in Allen, to play for a coach who is every bit as passionate about the game as Rosen.
The senior broke the coach's school assists record last week, and before Tuesday's game, Allen took Rosen to midcourt and gave him a basketball inscribed with that accomplishment. After another nine assists against La Salle, Rosen has 514 in his career, compared to 505 for Allen.
"I think my coach thinks it's a bigger deal than I do," Rosen said. "It's something, I guess, and I guess the idea now is to shatter it."
He'll get more opportunities when Penn's Ivy League season begins Friday at Columbia. Against La Salle, his nine assists easily could have been twice that many, but the La Salle defense kept getting in the way of what should have been easy layups.
Penn hung around despite trailing by 10 at halftime and by 13 with a little more than five minutes to play. The Quakers cut the lead to five points in the waning minutes, but couldn't hit the big shots they needed to fashion the upset and couldn't keep La Salle from putting away the game at the foul line. Rosen found himself taking shots as the clock was winding down, and shots when all the other options were unavailable. He went into the game shooting 49 percent from the floor this season, but made just 3 of 13 shots against La Salle. There will be other nights, however.
"Every time we play Zack Rosen, I think he's going to find a way to win the game," La Salle coach John Giannini said. "He's made himself into a terrific player, but the biggest compliment is that he's a winner. I don't worry about his shot. I don't worry about his defense. I just worry about him winning the game. He's that kind of kid."
Which makes it ironic that Rosen has built his reputation during a stretch of Penn basketball that has not ranked among the best. The Quakers haven't won an Ivy League title during his tenure and, unless something changes this season, he will leave Penn having never played in a postseason tournament.
"There's no excuses. There's no explanation," Rosen said. "It's been a great learning experience for me and an unbelievable time. And, to be honest, on Friday we're just getting started."
His goal after Penn is to continue playing basketball as long as possible.
"I'm a rat," he said. "If someone gives me an opportunity, I'm going to try to make the best of that one."
The opportunity he has now isn't over yet. There is still the Ivy season and still that final chance to lift his team to something special.
"Hopefully, we'll all start shooting well in the Ivies, but you can't control that," Rosen said. "The part you can control is defense."
The great lesson of basketball is that you can't control what the nine other guys on the court do, either. Some nights, it all works. And some nights, even one of the best players in the city can't change the tide of the game.
Losing stinks. Zack Rosen and Penn didn't need to be reminded. They already knew.
Contact columnist Bob Ford at email@example.com, read his blog at www.philly.com/postpatterns, and recent columns at www.philly.com/bobford.