Avinash: Tyrone Wallace. He has to run point capably or Cal is going to be an up-and-down team all season. Wallace has very good athletic talent but still doesn't have the greatest feel for the game. He is very much a 2 playing a 1, he wants to slash and attack at all times. That offense can rise and fall depending on his management.
A.W. Johnston: Tyrone Wallace. As a senior he needs to be a vocal leader and understand his responsibility for bringing along our two stud freshman. If he can improve his free throw shooting, he can cause the most havoc while defenses spend their attention of a few other big name players.
Ruey Yen: Yes, Tyrone Wallace will be a key player for the Bears, but for me the bigger unknown, and one that may put the Bears over the top would be the performance of Ivan Rabb. Wallace has already improved steadily the past few seasons that I trust him to be ready and solid. Jaylen Brown will be athletic and do some special thing to wow us. Ivan Rabb, on the other hand, is starting his Cal career with a bit of a question mark. While his rebounding skill is supposedly NBA-ready, Rabb's offensive game is a question mark with some folks thinking that Rabb might return for a sophomore year to polish his game more. As much as the Bears are loaded in the wings, they would need Rabb's inside game to stand out to truly be a NCAA title contender.
boomtho: Since Avi said Tyrone Wallace, I'm going to go with the freakish hybrid of Jabordan Mathbird. I'm assuming that most games Tyrone, Jaylen, and Ivan will be able to "get theirs" in a reasonably efficient manner (note: I'm assuming the infusion of talent is going to work absolute wonders in creating space, especially in the paint, for Tyrone). Thus, I think two critical players for us are Jabari Bird and Jordan Mathews. They're going to get a lot of clean looks from the perimeter, and their ability to consistently knock them down will be crucial. In addition, Cuonzo is going to ask a lot defensively of this team - I think Domingo, Wallace, Jaylen, and Singer are certainly up to the task; I'm a little less sold on Bird and Mathews being able to rebound and defend at a consistently high level.
Nick Kranz: Tyrone Wallace is probably the correct answer, but there's a chance that Jaylen Brown blows up and becomes Cal's go-to scorer by the time the Pac-12 schedule rolls around. He could be a Stanley Johnson/Shabazz Muhammad type of player who immediately dominates as a freshman even with plenty of talent around him. I wouldn't say that's the most likely scenario but it's in play.